I have been asking my this same question until I saw this and I know is answered from the above replies. But I think, is safe to leave it on if your account is log in on your personal computer which only you have access.
For own personal computer, it's not wrong to leave your account there. If you know how to deal with security, you will have no problem with this. I think it's been 2 months that I imported my account there without doing any log out. We are responsible to make it unaccessible to others.
Either hit forget account suggested by above users or you can just clear your browser cache as your ETH address detail is only stored in your browser.
Although Don't know that they will still store private key details in their database even after hitting forget password or not.
This will do too if OP is afraid of the word "FORGOT" as for newbies it might mislead them to what's on the noticed before they hit that button.