1. Don't let me down. 不要让我失望。
Don't worry. I won't let you down.

2. Let go of me. 放开我
Just let go of me.

3. let me out 放我出去
Mom, just let me out.

4. I can't let it out. 这事儿不能泄露出去
This is just between you and me, OK? I can't let this out.

5. Let your hair down. 你要放松
Hey, dude. Just let your hair down. Just relax and have fun.