PluginSandboxProfiles folders containing Adobe Flash Player, Google Talk, and Silverlight plugins

Thanks in advance.

a. Can anyone explain what the following 6 files are and why I am not able to delete them? I uninstalled Adobe Flash Player and have deleted all leftover Flash Player files except for these.

b. Below is one of the PluginSandboxProfiles folders. I'd like to delete all the files within the PluginSandboxProfiles folders associated with Flash Player, Google Talk and Silverlight, but MacOS Mojave is not allowing me to do that.

c. Anyone know what triggers all of these files to be added? Everything in the folder below was added on April 2, 2020 at the same exact time. I reinstalled MacOS around then, though I am unsure of the date.