You can find constituents that canceled their sustaining gifts by running a query.
  1. Create a new query
  2. On the Query Builder tab, click the dropdown menu next to Field Type and select Sustaining Giving Information
  3. Next to Field, select Status
  4. Click Add Field Clause
  5. Click the bottom dropdown menu and select Terminated By User
  6. Click Save
  7. Click Save Query
  8. Click Run Query to see the results
To understand what the other Sustaining Gift Status' mean, check out What do values for Sustaining Giving Information Status in the Query Tool mean.