You, as an individual, have a right against self-incrimination, but you're simultaneously subject to laws against tampering with or destroying evidence. You do

You, as an individual, have a right against self-incrimination, but you're simultaneously subject to laws against tampering with or destroying evidence. You don't have to hand over the incriminating evidence, or even tell the cops that you have it. But if they find out you did have it, and knowingly destroyed it to hide your illegal behavior, that is a legitimate additional charge.