currently, If I want to back-out changes to an entity after using ent_clone or ent_cloneskin and ent_setmesh/ent_setskin/vec_to_mesh commands I ent_remove the entity and recreate it using ent_create.

I looked but didn't find anything, but is there an easier way to restore back to the original state before the ent_clone or ent_cloneskin functions were called?

That depends on the changes. Some changes, such as morphing the entity in a different model, can only be taken back by re-morphing it. For most changes you can just copy the relevant part of the ENTITY struct in atypes.h into a temporary struct, and then copy it back.