Can i sell a phone that has been previously jailbroken, but restored, back to my carrier? I have an iPhone 6s that i'd like to jailbreak, but it is locked to a carrier. I wouldn't be unlocking it, as id like to sell it back to the carrier at some point in time. Is it possible for me to jailbreak, use tweaks and mods for a while, then restore my phone and sell it back?
Sure; provided that you don't brick it accidentally, restoring it in iTunes will remove any evidence that it was ever jailbroken.  When I bought my 6+, the 5S I sent back to the carrier had been jailbroken the entire time I owned it.  I restored it to factory before sending it back and no one mentioned anything.  Same thing when I updated from the 6+ to the 6S+.  Restored the 6+ and the carrier didn't complain.