1. "by default my pages removed from database"
Please be more specific of pages being removed. The Menu and pages will never be deleted at the Plugin installation. If home page is changed, you can always customize it from the Dashboard, but they are not removed. Still I'll revisit plugin code for removal of data at the time of deactivation of plugin (That's where pages created by plugin is removed).
2. "menu settings removed" Regarding Menus
New Menu will be created and might be shown in home page.
Please login to your WordPress dashboard -> Apperance -> Menus and check if the other pages are there. No Overwrite of menus or pages done anywhere in code.
3. "total database gone"
I am not sure, what you mean by total database gone !!!. If you be more specific it will be helpful to community get a better quality plugin.
thanks for sharing your experience.