Help

So I was cleaning my room and I found a thermos under my bed which had been missing for months and I opened it and it's really moldy and gross but the thing is I live with my parents and they're gonna be pissed at me if they find out it's been in my room festering for months how do I clean it without them knowing(is baking soda gonna work in the situation) My current plan is wait until like 1am when they're asleep amd clean it then hide it at the back of the cupboard and say nothing will this work or should I come clean and hope they don't kill me

Edit: thank you everyone for your suggestions! I have decided that I don't want to risk mould poisoning so I'm going to take it and throw it away somewhere subtly(not at my house) and then never speak of it again :)