Can I disable email but still use my Apple ID?

You can change the Apple ID email address and you won't lose any data or purchases. Note the restrictions in the article.

Apple ID Name Change.  * 

Make sure you turn of Find My Phone before signing out of the old ID. Once signed out and Find My Phone is off, then sign in with the new ID, then turn Find My Phone back on.

 What to do after you change your Apple ID or password - Apple Support  *  I suggest doing this before you change your Apple ID or password.

Hello Dosido Monster,

You may delete your email as long as it has been verified before you do so, but if you do then any verification emails or News will not be accessible. You can delete the Gmail though safely but it is not recommended, but again if you really want to you can but you just will only be contactable by phone number if you have one.

Hope This Helps