So I have the following
and I would like to remove the lines inside of the circle. I've tried the scissors tool, joining them then using the scissors, and outlining them using the pathfinder window then using scissors.
Make two closed paths with appropriately thick strokes and no fill; first a triangle and then a circle on top:
Duplicate the circle layer and place it at the top of the layer stack:
Make the triangle and the bottom circle paths active:
Then go to Window > Pathfinder... If you're OK with just getting rid of only the appearance of the inside lines, you can simply Alt+click on the 'Minus Front' button:
That produces this result:
If you need the paths inside the circle to be actually gone – just click 'Minus Front' without the Alt modifier... Then if needed you can select the remaining shape and the circle and press Ctrl+8 to create a single compound path: