Yes.  The easiest way is to flag your own activity… On the web, go to the activity page, click on the three dots next to the pencil icon, and a drop down menu will appear.  Click on “flag”.  You may be asked to provide a reason, choose “bad GPS data”. 

Either that or make your activity viewable to followers only. 

Alternately, you can try clicking “correct distance” which may fix a GPS error that resulted in this.

If I flag it, will it flag the whole ride, or can I just flag the segment?  The rest of the ride it read completely fine.

Sadly, it flags the whole ride.  People have repeatedly requested the ability to flag just one segment, but the company has never provided that option.

You can mark the activity as private or followers only so segments don't count towards the leaderboard. There's no way to control just a single segment though.

When all the other segments should count in the leaderboard I would split the activity in the middle of that segment. Then you have two correct activities instead of one with a glitch:

Hello @Blinky802 ,

We suggest you do not flag your own activities as this is not a correct method of reaching our support team. Learn more about the flag feature here: https://support.strava.com/hc/en-us/articles/216919387-The-Activity-Flag-Remove-an-Activity-s-segment-results-from-the-Leaderboard. 

We appreciate your honesty regarding the achievements on your activity. There are a few different options you can take to remove the achievement:
 
1. Split or Crop Activity:
You can remove a certain portion of the activity by using one of these tools: crop or split. If the achievements are only at the beginning or end of your activity we recommend using the crop tool. If these achievements are in the middle, you will need to use a combination of the split and crop tools. Using the split tool will produce two separate activities, which cannot be merged. For more information, see our article on how to split activities and how to crop activities.
 
2. Mark your activity for Followers or Only You:
Changing the privacy settings for the individual activity will remove the activity from the leaderboards. They may, however, continue to be visible as your own PRs but only when you are logged into your own account.

• On the web
  • Go to the activity and select 'Edit' (pencil icon.) Select 'Privacy Controls' to choose between 'Only You' or 'Followers.'
• On the mobile app
  • Go to the activity and select 'Edit.' Tap on 'Privacy Controls' to choose between 'Only You' or 'Followers.'

For more information, see our article on activity privacy controls.
 
3. Change your activity to 'workout' or 'indoor'.
You can update your activity to the activity type workout which will remove the activity as this particular type and remove it from competing in the leaderboards. Or you can mark the activity as being completed indoors which will hide the GPS data, thus removing any matched segments.
 

Hope this helps! 

@Lola - that is a very poor set of workaround options.  Why won’t Strava give us a simple way to disassociate a specific segment from a ride?  We can already click to “star” a segment or to “hide” a segment.  Why don’t we have a similar option to just simply say it shouldn’t have been matched to that ride?  A very simple thing to just have one segment get removed from the ride statistics.  All of the other options you proposed would take away from people’s activity stats and tracking.