This might be a stupid question but anyone know how to do this on a road bike, the rear derailleur cable is stripped at the end, pulled it all the way through the cable sleeves, but can't work out how to get it out of the shifters, where the barrel on the end comes out

Shift it into the smallest sprocket.
Feed the bare cable back to the STI.
Snip off some of the cable to make it easier to work with.
Depress the STI lever a little way, so the guide just behind the Ultegra top cap is visible.
Push and wiggle the cable and it should slide out.

When you put a new one back. Grip the bare cable and shift the STI to make sure it's working, just incase you've fed the cable loose into the body.

Just thought, I've assumed they're the older pattern with exposed gear cable outers and not the latest version 😳

Thanks Oldgit will try that, I tried finding something online ,sheldon brown and even Shimano's website , but doesn't show where the end exits from the changer

Again assuming they're the older style the little 'leaded' nipple can be well seated in the lever but it will come out.