Set an endpoint for movement tracker, in color tab

I was able to follow the instruction the following video, on how to blur part of a video, that contains sensitive information, such as the license plate number of a vehicle.

I'd like the tracker to stop, without me having to resort to pressing the stop icon, once it reaches a specific point of the video. Also, since said information, in this case the license plate number, IS NOT visible through out the duration of the entire, I'd like to have multiple or 'independent' nodes, with its own tracker each time, the said license plate or sensitive image appears.

Unfortunately the following video on keyframes in the color tab, was of little help to me.

The following image shows what I've done so far:
https://i.imgur.com/scSXOzR.png

1st edit: The following video was much more helpful on working with keyframes in the color tab

The keyframe panel on the right does not apply to the tracking panel keyfremes AFAIK. You can drag-select delete tracking data after the point you want the tracking to stop. If the feature leaves the frame, you can manually animate the power window for the frames that cannot be tracked....

I've 'dash-circled' an icon, in the attached image of this post, that permitted me to add a supposed keyframe within the 'tracker' window/box.

I'm trying to do a tracker within the first 14:26 seconds of the clip; i.e. 14.8 seconds in decimal format.

After tracker completes, the first 3.7 seconds (03:21), it stops and I have to press the play button, a second time, for it to resume, then I manually stop it, once it surpasses the 14:26 mark; i.e. 16.7 seconds in the attached image of this post.
What's the reason for me in having to press the play button a second time?

The keyframe panel on the right does not apply to the tracking panel keyfremes AFAIK. You can drag-select delete tracking data after the point you want the tracking to stop. If the feature leaves the frame, you can manually animate the power window for the frames that cannot be tracked....

Thanks for responding. Is there a video demonstrating 'drag-select delete' of said tracking data?

I've manually added a 4th diamond/keyframe marker in the attached image, at the current location of the playhead.

I'd like the 'tracker' data to the right of the playhead to be deleted.

1st edit: Selecting the 'line graphs' after the playhead, I was then able to press the delete key on the keyboard.
https://i.imgur.com/ysbbJta.png
https://i.imgur.com/qQjtzQ3.png

2nd edit: Despite deleting the tracked data after the 14 second mark, the blur still appears
https://i.imgur.com/fEHAmuM.png

3rd edt: I added a 3rd keyframe, one frame later, and changed the blur value to zero, and that setting takes places in proceeding keyframes.
https://i.imgur.com/yd5EsF3.png

4th edit: I may have figured it out, after clearing the tracking window, the tracker automatically stopped at the 2nd to last keyframe. The last keyframe is positioned one frame ahead, using the right arrow on the keyboard.
https://i.imgur.com/iBPn2qC.png

Unfortunately the polygon shape, still appears, despite disable all option in the respective keyframe
https://i.imgur.com/dD9eX26.png

Edit: It seems, the opposite facing triangles must appear, as shown in the last video of my updated first post. From there, tracker will stop at the respective keyframe without me having to press the stop button.
https://i.imgur.com/XqA3Uv5.png
https://i.imgur.com/1z08Zhi.png

5th edit: After selecting the last keyframe, I deselected the polygon option
https://i.imgur.com/IPxF8XO.png