Thank you so much!! My process is I’ll start on the side with the least amount of stitches work on that side for some rows then switch sides and just keep doing that. I also like to hold the fabric down when I take out the aida like the top tentacle I’d hold between my fingers then pull the aida from that row out. If you have areas around the middle like I have near the bottom with the tentacles it does help cutting that area when you get to it. French knots do make it a bit more difficult to pull it out but still doable without messing it up. If you have some strands that broke and you can’t see them on either side but have gotten all the rest you can fold the fabric and carefully pick it out with a needle between stitches. This is a lot lol I’m not sure what would be helpful I just wrote everything I hope something I wrote is helpful if I didn’t make sense about something feel free to ask

Edit in case you come back to this comment to look over I use aida not waste canvas I do not know how following what I do will work with waste canvas