The proper way to remove this is to go into the editor (Tools menu, Launch Editor), then create a new file, go to the armor tab, and on the bottom left, click the "New (Copy)" button. Find and select Chainmail in that list, and write down the unique Id that's in parentheses ("mChainmail"). At the top, enter a new unique Id (I recommend "mChainmaiA"), and on the right, find the box labeled "Replaces Thing Id". Put the unique Id of the original chainmail ("mChainmail") in that box. Now, in the center, find the Maximum Dexterity Bonus selector, and change that from 2 to 1000.
Save your new version of chainmail, save the file to the default directory (data/d20), and then press the "Test Now!" button on the top left. Now, chainmail will not have a max dex bonus, and you can email the file you created to anyone else who will be using this.
If you want something simpler, joaquin83 beat me to that answer.