Two ways..
1. In Kodi, disable auto updates by going to the add-on settings and left drawer... Auto Updates to Never or Notify
2. Identify the repo that has IPTV Stalker as an update and uninstall it. The only 'safe' repo for it is the tecbox/iVue guide repo, but it currently has version 9.0.19, which does not have the "send serial number" enabled. All other repos should be considered suspect.