Navigate your way to Class Types >> Classes and select your desired class.
Click the gear icon besides the timeslot you would like to remove, and click Delete.
Note. If there are classes with attendances i.e. customer/s are registered onto, then you will have to cancel these manually, by clicking the cancel option.
From the subsequent page, you have the option to refund the customer, and notify the customer/s of the cancellation. Once you have made you choices, you can click to cancel the class.
Repeat this process for any classes with attendances. Once complete, click the gear icon besides the timeslot you would like to remove, and click delete.