vim global command

The :global command is your friend - learn it well. It lets you run arbitrary :ex commands on every line that matches a regex. It abbreviates to :g.
To delete all lines that match "George Bush":

:g/George Bush/ d

The command that follows can have its own address/range prefix, which will be relative to the matched line. So to delete the 5th line after George Bush:

:g/George Bush/ .+5 d

To delete the DEBUG log entries:

:g/DEBUG/ .,+10 d

If you knew the stack trace was variable length but always ended at a blank line (or other regex):

:g/DEBUG/ .,/^$/ d

You can also execute a command on every line that does NOT match with :g!. e.g. to replace "Bush" with "Obama" on every line that does not contain the word "sucks":

 :g!/sucks/ s/Bush/Obama/

The default command is to print the line to the message window. e.g. to list every line marked TODO:

 :g/TODO

This is also useful for checking the regex matches the lines you expect before you do something destructive.
You can chain multiple commands using "|". e.g. to change Bush to Obama AND George to Barack on every line that does not contain "sucks":

 :g!/sucks/ s/Bush/Obama/g | s/George/Barack/g