You can create a temp schema under any user, and change the owner of your tables from tt to this schema.
e.g. ALTER SCHEMA temp TRANSFER tt.myTable1
you can see your table name changed from tt.MyTable1 to temp.MyTable1
Make sure tt no longer owns any object;
then delete your 'tt' schema;then delete your tt user;
After you re-create your tt user, then change all the tables owner to your new tt schema;
then delete the temp schema.
Good luck!