Exactly what setting are you referring to? Because the one they list on their website is in "about:config" [1], and anytime you go into about:config, Mozilla scares users about voiding their warranty. Only tech-savy power users are going to attempt that.
> In the address bar, type about:config and press Enter.
> 1. The about:config "This might void your warranty!" warning page may appear. Click I accept the risk! to continue to the about:config page.
> 2. Type pocket in the Search box above the list of preferences.
> 3. Double-click the extensions.pocket.enabled preference to toggle its value to false.
> In the address bar, type about:config and press Enter.
> 1. The about:config "This might void your warranty!" warning page may appear. Click I accept the risk! to continue to the about:config page.
> 2. Type pocket in the Search box above the list of preferences.
> 3. Double-click the extensions.pocket.enabled preference to toggle its value to false.
[1] https://support.mozilla.org/en-US/kb/disable-or-re-enable-po...