It’s quite easy to remove Marketplace installed items.
In the Welcome screen, at the top, click on Profile.
Click on the Content Manager.
You will see all your sim’s contents displayed.
Click on the item(s) you want to delete (you can do multiple, it doesn’t have to be one at a time).
When all are selected, click the Delete button.
These will then be removed, and they will show up in the Content Manager in the top left as Not Installed.
Clicking on that “Not Installed” will show them, when ready to reinstall them, again, select the one(s) you want and hit the Install button.
If the issue continues to happen, there is a much easier way to prove that addons aren’t the issue.
You can start the sim in “Safe Mode”
This loads the sim without any addons.
To do so, with the sim running, use Windows Task Manager to shut MSFS down.
The next time you start the sim, you will have an option to choose Safe Mode.
Ensure you aren’t running any outside program such as ForeFlight for the trial.