I want to lose!

Recently I've been playing now and then due to being busy. But recently I've been wanting to rank up. I play a couple of normals to warmup and head to ranked where I get destroyed. My mmr in normals I think is so low compared to my ranked and I have no idea why. I literally can not practice because I've been doing so well in normals where I've been destroying teams with ease. But that will get me as good as if I just played bots and thought I was good. When I hit ranked, the people I play with are equal or better in skill (both in my team and the enemy team) and it's almost like a wall I can't pass. I really want to do bad like I do in ranked but not affect my LP. It will help me get better. How do I get my normal's mmr up? I have like a 80% win rate in normals but like a 30% win rate in ranked in the last couple of months.