I want to Remove some custom fields by using changesets. Is it possible to remove fields using Change Sets deployment? Or is it dono manually in Production env.?
You can either use the migration tool or delete the fields manually. Change sets cannot delete metadata.
Changesets are strictly additive and not destructive.
It is possible, though semi-difficult, to delete fields from Eclipse IDE.
It's definitely possible with ANT or Migration tool, but you gotta weigh how much work it'd take to do it "manually" vs the methods mentioned above.
Often, I bite the bullet, and just do it manually -- it gets the job done