There's Symbol::delete_package available to clear a packages symbol table.

This may not return you all the memory you think for various reasons:

• it might be using XS code that doesn't free up the memory it claims
• if there are references to things created by package they are not going to go away unless their reference count falls to zero... Are things sitting in a cache somewhere? Could there be circular references?

There is also the fact that all of the perl implementations I've worked with do not return freed memory to the OS - so if that's what you're looking for I'm afraid you're out of luck.