How to remove several lines in the Vim editor using regex

A quick tip for those who use Vim: if you need to remove several lines that match a regular expression, you can achieve that by running:

:g /pattern/d

Let's say you want to remove the commented lines from the following file:

# This is a comment
def foo
end

# This is another comment
def bar
end

Run :g /^#.*/d, and your code will become:

def foo
end

def bar
end

Simple, right? :)