it's almost necessary to have the following in a time traveling device:

- ability to travel or ease of hiding
- has to be placed somewhere that would not obtrusive, or wouldn't just fall off a cliff when traveling between time

So I pick Delorean, assuming the DR Who time machine is just like the H G Wells one with some spiffy features.

But the Delorean has to be able to fly and has the Mr Fusion "throw rocks in it" power supply.

I would go into the past, throw away relics into the Mr Fusion, and then unmake existence.