Good move, the coastal roads around there are perfect for exploring on a bike and you will see way more than from a tour bus. Bring your passport, a valid motorbike licence, and some cash for the deposit, most rental shops there work this way. Book online before you fly so you can compare actual prices and avoid the overpriced spots right on the main strip. Plenty of options to rent a motorbike in Alanya are listed on this site
https://getrentacar.com/en-US/motorcycle-rental/turkey-alanya .