Can I use Monero to pay a Bitcoin accepting merchant in a untraceable manner?
If so what is the process?
Any business that accepts Bitcoin can be paid with XMR.to which automatically converts Monero from the buyer into Bitcoin that will promptly be sent to the Bitcoin merchant.
Shapeshift.io offers a similar service to xmr.to but with slightly slower payments (they wait for tx confirmations instead of scanning the mem pool like xmr.to) and much lower maximum transaction sizes.
The only caveat to the above statement is that the goods/services being purchased must cost less than the maximum transaction limits (As of August 2017, 20BTC for xmr.to and <1.5BTC for Shapeshift.io).
Although the BTC payment to the merchant can be traced back to xmr.to or Shapeshift, it cannot be traced back to you because your Monero payment to xmr.to or Shapeshift was untraceable.
For maximum privacy connect to xmr.to or Shapeshift over Tor.
xmr.to logs are deleted in the following manner:
To be precise, we purge your order from our database after the bitcoin payment we make on your behalf has 144 confirmations (about 1 day). After 2 more days, your order will be purged from our backups. That means all records of your payment will be gone from our system after 3 days.
If using Shapeshift, do not use the return address feature for an XMR address that can be tied your public identity.