There is no official tool. You could try the tips in Upgrading to the Newest Version of CIS - what to do if you have difficulties.
If you want to do it manually:
Start with exporting your configuration to a folder that is not part of the Comodo folder under Program Files. This way you can restore your configuration after the reinstall.
Uninstall CIS and reboot. Then run Comodo System Cleaner to get rid of registry keys.
Then delete the Comodo folders under Program Files, Program Files\Common Files, C:\Documents and Settings\All Users\Application Data\ .
For Vista/Win7
Users%username%\appdata\local, Users%username%\appdata\roaming\ and \Users%username%\appdata\local\virtual store
To remove the socalled Legacy Keys, which are otherwise hard to remove, open Device Manager from the command prompt using the following two commands:
set devmgr_show_nonpresent_devices=1
start devmgmt.msc
Then set Device Manager to show hidden devices under menu option View. Then see if there are Comodo Internet Security related drivers left in non Plug and Play drivers. If so select the driver → click right → uninstall. Do this for all present drivers. Do a reboot when it has been requested…
Now delete the following:
C:\boot.ini.comodofirewall (this file may not exist).
WARNING: Do not mistakenly remove the original “boot.ini”.
C:\WINDOWS\system32\drivers\cmdGuard.sys
C:\WINDOWS\system32\drivers\cmdhlp.sys
C:\WINDOWS\system32\drivers\inspect.sys
C:\WINDOWS\system32\drivers\cmderd.sys
C:\WINDOWS\system32\guard32.dl
C:\WINDOWS\system32\drivers\sfi.dat (this file belongs to stateful inspection of the AV )
a. HKEY_CURRENT_USER\Software\ComodoGroup\CFP and HKEY_CURRENT_USER\Software\ComodoGroup\Comodo Internet Security
b. HKEY_LOCAL_MACHINE\SOFTWARE\ComodoGroup\CDI\1 *
*(If you have other Comodo products installed, delete only the values
for CFP)
c. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services
\cmdAgent
d. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services
\cmdGuard
e. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\cmdHlp
f. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Inspect
fi. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services
\cmderd
g. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services
\cmdAgent
h. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services
\cmdGuard
i. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services\cmdHlp
j. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services\Inspect
ji. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Services
\cmderd
k. KEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Services
\cmdAgent
l. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Services
\cmdGuard
m. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Services\cmdHlp
n. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Services\Inspect
ni. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Services
\cmderd
o. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmdAgent
p. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmdGuard
q. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmdHlp
r. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
\Inspect
ri. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
\cmderd
s. HKEY_LOCAL_MACHINE\SYSTEM\Software\Comodo\Firewall Pro
t. HKEY_USERS\S-1-5-21-1202660629-746137067-2145843811-1003\Software\ComodoGroup\CFP
u. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_CMDAGENT *
v. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_CMDGUARD *
w. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_CMDHLP *
x. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_INSPECT *
xi. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_CMDERD *
y. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Enum\Root\LEGACY_CMDAGENT *
z. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Enum\Root\LEGACY_CMDGUARD *
aa. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Enum\Root\LEGACY_CMDHLP *
bb. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Enum\Root\LEGACY_INSPECT *
bbi. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Enum\Root\LEGACY_CMDERD *
cc. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Enum\Root\LEGACY_CMDAGENT *
dd. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Enum\Root\LEGACY_CMDGUARD *
ee. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Enum\Root\LEGACY_CMDHLP *
ff. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Enum\Root\LEGACY_INSPECT *
ffi. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet003\Enum\Root\LEGACY_CMDERD *
gg. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_CMDAGENT *
hh. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_CMDGUARD *
ii. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_CMDHLP *
jj. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_INSPECT *
jji. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_CMDERD
kk. HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\CFP_Setup_3.0.14.276_XP_Vista_x32
ll. HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\CFP_Setup_3.0.14.276_XP_Vista_x64
mm. HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\CFPLog
nn. HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\CPFFileSubmission
oo. HKEY_LOCAL_MACHINE\SYSTEM\Software\Comodo\Firewall Pro
Sometimes it happens that you can’t connect to the internet after uninstalling, using the unofficial clean up tool or trying a manual deinstallation. Then the Inspect driver is still present and needs to be uninstalled.
How to uninstall the CIS firewall driver when it stays present? Look up the properties of the network connection, select the Comodo Firewall driver and uninstall it. See the attached image.
Now reboot back into Windows and CIS should be gone and you should be able to install it again.