The best way to do this is to set the total number of spots to equal the total number already sold. It will be displayed as "Full" on the front end.
For example, if you've sold 10 out of 15 available spots, change the Total Spots to 10. Or, if you've sold 0 spots, change the Total Spots to 0.
You can edit the Total Spots by going to Schedules in the Sawyer Tools menu, clicking on the scheduled activity, clicking Edit on the top right, and scrolling down to Total Spots.
Once the Total Spots matches the number of students enrolled, the class will be sold out.
When a scheduled activity is sold out, it is displayed in the widget but it is not purchasable by customers.
If you have the Waitlist feature enabled, customers will still be able to express their interest in joining.