how to ReadOnly Setting to show plugin installed or uninstalled State?

[zbaig]

Hi All,

i have a table for bad-words Filter and i do not want to drop it on uninstall.

i want a read only setting will be manage able only from backend on install or uninstalled.

how i can make a setting for plugin which is read-only for admin.
admin will see it read-only and can not change.

i will use this setting in my plugin function for is_installed_check rather than db exists or not....