After you create a join, you can change the settings you specified when you created it. You can remove one (of multiple) joins from a feature layer, or remove all joins from the feature layer at once, restoring the properties for that layer to its native data only.
To modify a join
The settings are the same ones you used when you created the join. For example, you can change this join from One-To-Many to One-To-One to get rid of extra features created by the original join.