When workspace has issues like some field was deleted/lost, the autolinking becomes broken. So I’m trying to delete the autolinking criteria and I can but then there is no way to save the field’s settings changes.
Once a field is established as using autolinking, there needs to be at least one valid rule (and no invalid rules).
Provided you meet those criteria, you should be able to save the relation config.
Can’t I delete autolinking?
Unfortunately, no.
An autolinking relation is a readonly relation, somewhat akin to a formula field, and doesn’t currently support being converted to a regular field.
That’s an awkward experience being locked into the readonly stuff and being unable to change the situation - only by re-creating the field.