The domain you have supplied is already in use.

[fotoshopmaster69]

I have changed my main domain back to the x10hosting sub-domain but when trying to change it back to the regular domain it says "The domain you have supplied is already in use."

 

[descalzo]

etiv.etiv.in is listed as a subdomain. If you are trying to add etiv.in , that is the reason.

Remove the subdomain (which you should have done before removing the main domain) and then try again.