In addition to Hood’s great advice (which should see you fine); you can also move back the way you have come from, almost repeating the last blob but without any filler. Like stroking the last dab with the dying arc if that makes sense?
Or as you get to the end of the run and let go of the torch button, as you see it cool just arc up again for a split second to slow the cooling. A quick blip, if you like.
In the ideal world, you'll set a few seconds of down slope on the machine if possible.
And when you tack stuff together, try and tack on the corner, then you'll have a nice tack free joint to weld.