How can I change my email?
It's not possible to change your email.
You can open a new account through your new email, but your profile history (points, levels, rank, etc) will be lost.
Remember that there are 3 login ways: Facebook, Google and your personal email.
Each login way corresponds to a different account.
If you created 2 accounts via different ways (i.e. 1 Facebook and 1 Google), you'll have 2 different accounts.