Before you proceed, you need Spaces installed on your phone.
How to Leave a Space?
Step 1 - Open the Space you want to Leave and click on the three-lined menu icon located on the top right corner of the screen.
Step 2 - Click on Connected.
Step 3 - On the bottom of the screen, click on Leave Space > It would ask for confirmation "Are you sure you want to leave this Space? > Select Leave Space.
You are done!