Sorry, I didn't read the OP closely enough.
Make a block selection (Right click and drag), then Delete
A slightly faster way, if you want to delete to the end of the line, is to do Edit > Select Block (Ctrl+B), then cursor down to the bottom of the line range you want to delete, then hit Ctrl+e to cut-end-line on all the selected lines.
You can also do this by creating multiple cursors.