There are ways to bulk create cohorts, but apparently not to maintain them (eg edit or remove)

e.g. I created over a 100 cohorts using CSV file, which should now contain different students.

I can't find a way to remove students from a cohort using CSV.

I also can't find a way to remove cohorts using CSV .

I suggest adding an extra field, something like:

username,password, firstname,lastname,email,cohort1,removecohort
jackbrown,Pass5678,Jack,Brown,jbrown@example.com,London Contingent,Oxford Contingent