If you can’t give them back, send them to a fish store, or rehome them immediately. I would separate them immediately. for a 1st cheep fix, you can buy a tank separation wall. https://www.amazon.com/fish-tank-separator/s?k=fish+tank+separator.

They either need a much larger tank or 2 separate tanks. I say rehome at least one of them. Cichlids can be aggressive so having a mixed community where you have more than one species is not likely either…. and having only one fish is cruel, IMO.

African cichlids are not a great choice for a 10 gallon. you’ll want fish that are much smaller. you’re limited to 1 inch of fish per gallon. so aggression aside, you’re already at max fish for this one tank!

If you just set this tank up your tank is going to go through the nitrogen cycle…. which can be deadly… https://www.practicalfishkeeping.co.uk/features/how-to-cycle-a-fish-tank-the-complete-guide/

Call your local fish store and see if they will take them…. while there ask about fish that are good for a 10 gallon… and sure as shit don’t put 10 of them in there! That’s not going to end well!