Hi,
Kayece here, An Independent advisor and a user just like you. I will be happy to assist you today.
Please follow the steps provided on the link below to close the Epic Games launcher and uninstall it.
*Press the key together: Ctrl + Shift + Esc to access the Task Manager;
*Under Processes, locate EpicGamesLauncher;
*Right-click on it and select End Task;
Try uninstalling the app again.
Open the Start Menu > Click Settings > Click Apps
Select Apps & features from the left-hand side menu.
Select the Program or App that you want to uninstall from the list that appears.
Click the uninstall button that shows under the selected program or app.
If you still receive the same error, please completely turn off your computer or laptop and then turn it on again after a few minutes. Try uninstalling it again.
Sources:
https://answers.microsoft.com/en-us/xbox/forum/...
https://answers.microsoft.com/en-us/windows/for...
I hope this helps. If you need more assistance, please let me know.
Stay Safe!