English Translation
You don’t have to forget that.
Likely, the intended meaning here is “You must not forget that” rather than “You don’t have to forget that” (which would mean: It’s ok if you remember it but it would be better for you to forget it)
You don’t have to forget that.
Likely, the intended meaning here is “You must not forget that” rather than “You don’t have to forget that” (which would mean: It’s ok if you remember it but it would be better for you to forget it)