Step One: Navigate to the RobZ front page
Step Two: Read the bit that says its a multiplayer mod
Step Three: Uninstall

Shameless plug, but I edited all the vanilla campaigns (except japan and origins) to work with robz. No more blue soldiers, more ammo, and some tweaks here and there. :) https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2299577549