Uninstalling fop2admin should not interfere at all with Freepbx after the uninstallation. If files are removed, there is nothing that could affect FreePBX. So, I have no idea what is wrong in your setup. It is quite simple, if a module is NOT present, it cannot break FreePBX as the module itself is not loaded, there are no files, no hooks, no callbacks, etc. So what you say it does not make any sense to me.
If in doubt, remove the module directory by hand, usually in /var/www/html/admin/modules/fop2admin , just remove the whole directory.
fop2 and fop2admin are non intrusive in its nature. I think you have some other kind of problem.