It depends where the pop-up reminder is coming from. A screenshot would be helpful.
If you installed Flash Player manually, a reminder will pop-up to uninstall Flash Player.
As of Windows 8, Microsoft embeds Flash Player ActiveX Control in IE and distributed all updates for the embedded version of Flash Player. Adobe's uninstaller will NOT removed the embedded Flash Player ActiveX Control as it's managed/owned by Microsoft.
If you wish to uninstall the Flash Player ActiveX Control embedded in IE Microsoft has released an update, https://support.microsoft.com/en-us/help/4577586/update-for-removal-of-adobe-flash-player, to remove the embedded Flash Player ActiveX Control. Please read through this document carefully before doing anything. This support page has a link to the Microsoft Update Catalog, which contains 43 different files for the different Windows versions and architecture. Make sure you download the correct file for your Windows version and architecture. If you experience issues with this update, please contact Microsoft as it's their update, not Adobe's.