This sort of problem and error message happens when the lens-moving motor senses an obstruction. The camera assumes the obstruction to the lens assembly's moving outward is, that the lens cap is still on (which would obstruct outward motion of the lens assembly), and so signals to remove the lens cap.

Try inserting the edge of a piece of paper into the crack around the lens assembly, where it meets the camera case, and moving it about a bit, then removing it. (The idea is to try to dislodge anything that might be jamming the camera lens mechanism.)

Also try removing the batteries, and leaving the camera on a (dry, non-humid, non-dusty) shelf for overnight. Then put the batteries back in and try the camera again.

How old is the camera? in months or years since you bought it.

Has the camera been dropped or otherwise subjected to mechanical shock(s) in its lifetime?
Has the camera been operated in or subjected to, temperatures below 32 degrees F (freezing point) or above about 100 degrees F ? Has it ever been subjected to a humidity higher than 85 % ?

Has the camera been operated in a gritty or sandy environment, such as a beach, a seaside, a construction site, or the like?