As with all memory-resident AV software , you can only have one installed at any one time.
Indeed, most AV software will abort installation if it detects similar software already installed, as running two can cause conflicts & system instability.
The standalone Comodo Firewall, if that's all you want, is on the right-hand side of this page:
https
/personalfirewall.comodo.com/?prod=antivirus&track=2199&s_track=7639&key5sk0=2199&key5sk1=7a22a09cb1a7463ae20f033d218d729d81e5dd10
After Comodo Firewall is installed & working, head over to Control Panel & disable the default Windows firewall (The Comodo FW installer may do that automatically, I can't remember). Having two software firewalls active can cause settings conflicts & possible...