You can easily change your account email by logging to your Hostinger account.
Once you are logged in, click on your Avatar and choose Account Information (or My Profile) option:
In new interface
Once there you will see the Profile Information section, click on an arrow near Email from there:
Enter your new email address and click on Save changes:
In old interface
In the left part of your Profile page click on Edit profile. All you will need to do is enter a new email address and click on Save Changes: