Reselling a Glowforge is supported, but please be sure to coordinate your sale with Support to ensure that the new owner can access the GF.
The new buyer may want to see proof that your GF is working (and not disabled in the cloud) so you should be prepared to demonstrate that the printer works, if you are asked to do so.
You should also specify your location, details about what you are including in the sale (ie: any ProofGrade materials and especially the GF shipping carton) and whether you can ship it or will only do a local sale. And an asking price couldn’t hurt either. Best to edit the thread title to say something like “GF Pro for sale in Houston” or wherever you are.
Also, you and any prospective buyer should read this Support bulletin to be prepared for the transfer. It can take a couple of days.
Good luck with the sale!