"Romex" (a brand name of a NM/B type cable) is not rated for wet locations.
You cannot strip the sheath because the wires inside the sheath are not rated at all without the marking on the sheath, and the sheath (jacket) needs to extend at least 1/4" into every junction box that a cable enters. And they were not rated for wet service in the first place.
So, every outside conduit is defined as (and usually is) a wet location. You need a wire type that is rated for a wet location - THWN, THW, XHHW, etc. The "W" is the relevant part. In smaller sizes THWN or THWN-2 are most common. Most "THHN" is also marked as THWN or THWN-2 (and possibly also MTW, and various other ratings)
For 20A at 60 feet a single Multi-Wire-Branch Circuit (MWBC) running on 4 12Ga Copper wires will do. One green or bare for ground, one white or gray for neutral, and two from one or more of the other colors for hots. They will connect to a two-pole 20A GFCI breaker in the house, and something to act as a local disconnect/shutoff at the shed.
If any of the conduit is above-ground, that part needs to be Schedule 80 for protection from damage. The top of the conduit (not the bottom of the trench) needs to be at least 18" below ground (more if a driveway is being crossed, less if protected by concrete...) Frankly I'd suggest just using schedule 80 for the whole run, it's not that much more expensive from a proper electrical supply (orange or blue boxes generally won't have any at all) and it's much sturdier.