The interface for the Electric Guitar Track is a little bit different than a Real Instrument Track (shown in Léonie's screenshot .
1) Go to the same Track Info window
2) When the left Tab is selected (Electric Guitar), click on the Edit button in the right upper corner. (the button turns into a "Done" button).
3) The amp pictures changes to show the rear view of the amp.
4) Now you can see below the effect plugins (in amp rear view) with the Noise Gate instead of the amp controls (in amp front view).
Hope that helps
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