How do I get ride of the red exclamation on my apple watch?

If you see a red exclamation mark or a recovery logo see this article 

The process is only suitable for Watch series 3 or later, OS 8.5 Onwards and iOS15.4 onwards only 

https://www.youtube.com/watch?v=l3Y2TBTfHTI 

Otherwise make a genius bar appointment to have it recovered.  

If you completed that troubleshooting and the problem is not resolved then reach out to apple support Click here > Contact - Official Apple Support  or phone numbers Click here > and or Genius Bar Reservation and Apple Support Options - Apple