In vanilla Config\XUi\controls.xml...
inside <players_header>:
<rect depth="1" name="ping" width="80" height="46" pos="1129,-6">
<label depth="1" name="text" pos="0,-63" height="42" text="PING" text_key="xuiPing" font_size="26" justify="center" pivot="left" />
</rect>
then inside <players_entry>:
<rect depth="1" name="ping" width="80" height="46" pos="1129,-6">
<label depth="1" name="pingText" pos="0,-15" height="38" text="--" font_size="26" justify="center" pivot="left" />
</rect>
These two are probably what makes the game show the ping column in the table when you press "I" in game to see the list of players.
With that said, you could probably target both entries with your own modified controls.xml that would contain two <remove> commands with xpath. I haven't tested it, so I have no idea what would it look like in game, but it's the start...
Code:
<configs>
<remove xpath="/controls/players_header/panel[@name='header']/rect[@name='ping']"/>
<remove xpath="/controls/players_entry/rect[@controller='PlayersListEntry']/rect[@name='ping']"/>
</configs>