is it possible to delete bill without delete an item receipt? if yes then how?

no record can be deleted if other record are referencing it. You have to remove the applying record or transactions first, in this case the item receipt. Note deleting item receipt doesn't affect GL because receipt doesn't have and GL impact and it can be easily recreated without any issues from PO.

@Sam-I-Am i just wanna correct my que is it possible to delete item receipt without deleting Bill bec firstly we did po > item receipt > bill so item receipt is reffered to bill normally we can't but in production account happening

yes you can with right permission becasue it doesn't have any GL impact. In fact just few minutes ago I deleted one receipt because some reclass was needed for PO and bill