You can see a list of all the segments added to your report using the Resources > Segments menu. You can also display this list by selecting a component with an added segment, then clicking 
Using the segment list, you can:
- See information about each segment in the report
- Edit the segment definition in Google Analytics
- Fix segments that have undergone a change of ownership
- Turn segment synchronization off and on
- Remove segments from the report
Edit a segment
Click 
Fix a segment
If the owner of a segment loses access to that segment, then that segment will no longer be synchronized with Google Analytics. For example, the owner might be removed from the Analytics view where that segment is defined. This can also happen when you copy a component to a new report that doesn't have that segment added yet. You can fix this situation using the resource manager.
Segments that have access or sync issues are marked with a warning icon in the properties panel. Click 
Turn synchronization off and on
By default, Looker Studio keeps your segments in sync with your Google Analytics view. Use the Sync with Google Analytics checkbox to turn synchronization of that segment off and on.
Learn more about segment synchronization.
Remove a segment from a report
To remove a segment from a report completely:
- Edit the report.
- Select the Resources > Segments menu.
- Locate the segment in the list, then click
Remove.
Removing a segment in this way deletes it from the list of added segments and prevents other editors from being able to use that segment in the report.