When you paste a block of text into a Putty window, many times you’ll get an increasing number of leading tabs. Not so if you use gnome-terminal (IIRC). Quite annoying in a Windows world.
Strip tabs and spaces out from current position to the end of the file with:
Or perhaps you only want a small block in the middle of the file changed. First, turn on line numbers.
Then search and replace on specific line numbers (in this example lines 15 through 41).
Then use Ctrl-V (down arrow or h,j,k,l keys to select block) and hit “>” to re-indent. Works much better than reformatting by hand.