How do I whitelist an IP in the Shifter dashboard ? How can I add/remove IPs from my whitelist ?

In your account dashboard click on Manage on the membership that you want to configure geolocation. 

In order to access the configuration menu click on “Manage” for your selected membership plan and you see the configuration menu. 

In the configuration menu you need to add your list of Authorized IPs before accessing your list of proxy ports.

Just copy paste the list of authorised IPs or add manually and click “Save” after every change (the list of authorised IPs represents every device IP that you plan to use when accessing your proxies - it can be your web servers, desktop computers or mobile devices) 

Keep in mind that it takes 5 minutes before the changes you entered in the configuration menu to be activated in the system (adding an authorised IP address and then immediately trying to access the proxy ports from that authorised IP address will not work as the 5 minutes have not passed).