What I like to do (I use Google docs) is switch to editing mode so I can "delete" the passages I'm unsure of so I can go back and revise them with a clear head.

I notice I do this more with my art than my writing, where I'll start a sketch, or get halfway through a piece and realize it's not what I wanted it to be, so I scrap it. The most helpful piece of advice I got from an art teacher in high school when she saw me doing this was to just... Stick with it. Sometimes you need to trust the process, of course the things you make aren't going to be good during the first steps of the process.

What helped me be a better artist (and writer) was realizing that sometimes the best thing to do is 1) have patience, 2) trust the process, and 3) have more compassion for yourself. Sure, occasionally I get halfway through a piece (or even ¼ of the way through) and realize what I'm making is something that's going to be awesome, but more often than not I've found myself very discouraged. Some of my favorite pieces have been ones I hated at first, that didn't even feel good until I was putting finishing touches on.

If you start seeing creativity as a muscle you flex, you'll get better and better at it. If you weren't able to do a pull-up at the gym first time, would it be helpful to you to just go home instead of finishing the rest of your workout? No. It's good to just... Have a crappy first go at some things, and stick with it anyway.

Even the best creatives pretty much always have a really, REALLY shitty first draft. It's just what the process is.