Both sentences are correct. は is a marker for emphasis which turns to mean "theme/topic", which happens to mean "subject". It is used by adding to other markers which you want to emphasize, like: ここに本があります　→　ここには本があります。 あのひとと気があう　→　あの人とは気があう。 However, は disappears when it is added to the markers; が、を、and sometimes に これがお茶です。→　(これがはお茶です)*　→　これはお茶です。 お茶を飲みません。→　(お茶をは飲みません)* →　お茶は飲みません。 The sentence お茶は飲みません emphasizes お茶(を）、whick implies you drink other beverages like コーヒー、水、and so on, like: お茶は飲みませんが、水なら飲みます／飲めます。

は is used as the subject marker so the first sentence would be "The tea won't drink" which sounds weird because tea shouldn't be able to drink anything を is used to mark the object which the verbs acts on so the second sentence would be "I won't drink tea" which makes much more sense. I added an I in the beginning of the sentence because the japanese sentence did not have a subject (I/he/she/it/they) which is a natural thing to do in japanese.