Hi sander9860
If you've completed all games from that round and have no more left to play, then yes its safe to withdraw.
It shows on this page
You are allowed to withdraw from a tournament at any time using the Withdraw link located on the right hand side of any tournament homepage. However, withdrawing from a tournament while you have games in progress will automatically cause you to forfeit all of the tournament games on time which will negatively affect your timeout % ratio and your rating, even if no moves have been made.
Once I have played all my games in a round and am out of the running for continuing/winning a tournament, may I withdraw from the tournament so that it doesn't clogg up my current tournament screen? Are there any adverse consequences for doing so? And if I have won some paltry amount of points, will I still get them?