Hi sillyemma,
To remove a contact from Do Not Disturb, we recommend that you try the steps here: Use Do Not Disturb with Focus on your iPhone or iPad - Apple Support
To perform the recommended troubleshooting steps via the link above, complete the steps in the section titled "Change your Do Not Disturb settings."
If you don't want to be disturbed at a certain time, you can set a schedule and change other Do Not Disturb features to help you concentrate.
1. Go to Settings > Focus.
2. Tap Do Not Disturb.
3. You can select allowed or silenced notifications from people and apps, connect your Lock Screen or Home Screen, have this Focus turn on automatically, and add Focus filters.
We recommend the steps above because they will show you how to customize the Do Not Disturb settings on your iPhone.
Please let us know the outcome after giving the above steps a try.
Thanks for using the Apple Support Communities.
Cheers!