The Sorcerer doesn't make a pact.The Warlock and the Sorcerer are identical.
Both make a pact to have their bodies magically transformed by a patron.
The Sorcerers' powers are "genetic". Either from an ancestor passing down or an event altering their "genes". It's just that D&D doesn't speak of genes. The closest would be a truename and I believe sorcery is part of your true name.
The issue isthat D&D doesn't elaborate much on the difference of Magic in your Genes and Magic from a Pact. Other than that they are different. There is no way to strip a sorcerer of its magic barring polymorphing. And no one except maybe deities can make them purposely outside of the "old fashioned way".