The Share Access option allows you to retain control of the domain while granting access just to certain domain editing features to your customers or co-workers.
The domain will show up in another account with limited modification options.
NOTE: If you wish to use this option, you need to ask the destination user to
create a separate account with us.
Check out this KB article on how to share access with another Namecheap user.
If you have any questions, feel free to contact our Support Team.