You can also try selecting the lines and pressing Ctrl Enter (or Command Enter). This will make it add - [ ] before each line (that is a Dash, Space, Open square bracket, Space, Close square bracket, Space).
Then you can do a search and replace (I think Ctrl h by default) and search for what is enclosed in parentheses here: (- [ ] )
(Dash, Space, Open square bracket, Space, Close square bracket, Space)
And Replace with what is enclosed in parentheses here: (- )
(Dash, Space)
I only add the parentheses so you notice the space. Also I do this because if I tried to isolate it on its own line for clarity, it would be formatted to show a checkbox or bullet here on the forum.
As a side note, you can use + or * instead of dash. This can be helpful in cases where you are doing searches for the bullet formatting but have lots of Dash Spaces within your note content that would also be returned in these searches. And if you ever wanted to switch the + to - you can just do a search and replace (assuming you don’t use + in your note content as well).
I hope that helps.
Thanks.