Do not disable System K2 Plugin. Try to create an override of the K2 template, if you haven't already, (read here getk2.org/documentation/tutorials/174-templating-with-k2-and-the-concepts-of-sub-templates about K2 overrides and how they work) and modify the register.php page. You can comment out the parts you do not want your users to fill in when they register as long as they are not mandatory.

no problem B) I Edited the file register.php
Tanks for response
The edited file sent to you! if you look
and my site from register zoombox.ir/index.php?option=com_users&view=registration

Thank you for sharing this. Glad you have worked this out.