unable to remove user from sharepoint group

Hello All,

I have come across the strange issue where i am not able to remove user from sharepoint group though inheritance was broken long back however if i try to remove  the user from parent site it gets deleted automatically from subsite but if i try from subsite not getting deleted. and taking me to error page. Ananlyzed the ULS verbose logs but not got any significant error regarding that. Main interesting point is able to delete the user in sharepoint group through Designer.

Thanks,

Me