throw in the

throw in the towel

To give up on some endeavor; to quit or abandon something; to admit defeat or failure. I've been working on this book for over a year, and I'm getting nowhere with it. I think I'm ready to throw in the towel. After trying their hand in the mobile market for just a few years, the company is already throwing in the towel after finding very little success.
See also: throw, towel

throw in the

towel/sponge
To admit defeat; give up.
See also: throw