Deleting an unwanted email from account.

If his account was the one set in Media & Purchases, the items were purchased with his account and you have to use that account information for updating or re-downloading apps. If you have removed his information from Media & Purchases, that information is not there and your device will ask for it if you have automatic updates set, or even if you are manually updating. The normal solution is to delete the app and download it with your account. This could potentially involve data loss. The other typical solution is to set up family Sharing. To learn how to set up Family Sharing, read this support article --> Set up Family Sharing - Apple Support

Note that a password and a passcode are not the same thing and are used in different places. You mean password. If he changed his password since it was set on your device, obviously the old information is no longer valid and you would need the current information, or do one of the solutions in the previous paragraph.