The only way to remove your penalty is to wait the required time for Tier 4+, or to play the required games for Tiers 1–3. We cannot manually remove the penalty, nor can we restore any MMR/LP you might lose as a result of leaving a game or going AFK.

How do I get out of low priority queue in lol?

To leave the low priority queue and avoid its penalties, summoners need to complete at least five matchmade games without abandoning the matches early. Declining or not accepting a match will also result in the queue's timer being reset.

How long does it take for LeaverBuster to go away?

Leaver Penalty Applied The LeaverBuster system will automatically kick players who remain idle for 5 minutes. If a game doesn't end (for example for server issues, or because every player left the match), no penalties are given out. Punishment (All matches): No XP granted for the abandoned game.