The name that someone chooses for themselves, rather than the name they were born with.

No, a nametake would be the person who's name comes from another person. For example, Dr. King would be Martin Luther's nametake. After all, a namesake is a person who has been named after - so the reverse would not be the exact same thing.

No beef/feelings - just sayin

The reverse of namesake; a person you are named after.