You can only perform topless in free mode and not nude.
The purpose of Free Mode (among other things) is to entice potential clients into a paid-for mode, which will be much harder if you are already appearing nude.
Below, you can see how to disable/enable Free Mode:
Go to My DirectCam
Click on DirectCam Settings under ACCOUNT SETTINGS
Tick/Untick the checkbox labeled Enable Free Preview Mode
*Note: You may also select the maximum period or within any period a user can view you in Free Preview Mode