Hello,

To do this you will have to modify the current form control or create a new one. Currently, there is the User Avatar Selector used (/CMSModules/Membership/FormControls/Users/UserPictureEdit.ascx). You can see that in CMSSiteManager / Development / System tables / User / Alternative forms / Edit Profile / UserAvatarID. For more information on developing form controls please check our documentation.

Best regards,
Boris Pocatko