how do I remove a range of lines?

RouterOS General
1

Use WinBox, there you can select and delete as many items as you like.

2

Apart from the obvious answer given, a range of lines of what ?

3

Generally line numbers don’t exist on ROS, they are generated by print command. So executing remove numbers=300-500 is only possible after printing the section (and running same remove command without re-running print command would fail). In case where list is long (several hundreds or thousands of lines/items) using pattern matching is the right thing.