MS SQL -- GetDate(), without -, subtract 7 days ?

Below works, but updates to YYYY-MM-DD with DD of 3006 instead of taking 7 days away.

How can I change so it
 1. updates to YYYYMMDD without "-" and
 2. subtracts 7 days ?

update subscriptions
set parameters =
    substring(parameters, 1, 67)  +
    (select CONVERT(char(10), GetDate()-7,126)) + --ORIGINALLY substring(parameters, 68,8)   +
    substring(parameters, 76, 73) +
    (select CONVERT(char(10), GetDate(),126)) + --ORIGINALLY substring(parameters, 149,8)  +
    substring(parameters, 157, 999)
where subscriptionID in
   (
      --'E6B59B45-2C51-4A6F-906D-CBA4A48371F0',
      '379BC5A4-7F1D-4295-BD11-756154B83789'
   )