How do I turn off do not disturb

You can disable Do Not Disturb in the Control Center.

Swipe the Control Center up from the bottom. Find the Do Not Disturb Button, just below Screen Rotate Lock and Screen Mirror, tap and deactivate the active profile.

If Do Not Disturb or another Focus profile activates automatically, then a Schedule is active.

To disable or delete this schedule, go to:

Settings → Focus → Select Profile → find SET A SCHEDULE → Tap into the time → tap Delete Schedule or just deactivate.

You can read more about how to use Focus here:

Use Focus on your iPhone or iPad - Apple Support

Open Control Center.

Access Control Center on your iPhone - Apple Support

Then touch and hold Focus.