I can’t leave public workspace.
Hello @jiangzm, Welcome to the community 
You can directly click the home button (on top-left corner) and the workspace will be closed. 
Hi @sahuvikramp, Thank you for your reply.
Clicking the home button will close the current workspace but the access history still has these public workspace.
Hello @jiangzm, You are already out from those workspaces. The workspaces shown are not yours unless you fork it. Recently visited just allows you to switch faster to your last visited work (in case you forget their name, and it was helpful for you).