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Keep in mind i'm on a nougat rom so this method isn't the only one for you. Your device has to be rooted and you need a theme engine. For nougat it's the substratum engine.
If you have that all you need to do is download this app Lock Clean
You must use an earlier Substratum so uninstall current, get Substratum 854 and LockClean (tested 2.1 from play store). Once done you can revert to latest Substratum and the changes will persist.
Working fine on Samsung S8+ G955FXXU1AQI7
Note - make sure before OTA you remove all overlays as usual from manager and view all apps within settings and remove the left over lockclean entries, similar to com.android.systemui
S7 edge stock, no root, works for me, together with Lock Clean Substratum app: img
I cannot, however, change the lock screen wallpaper to KLWP at all :/
If you have Substratum you can use this: https://play.google.com/store/apps/details?id=com.kohlewrrk.lockclean&hl=en
If you have Oreo (or root) you can use substratum and lockclean (https://play.google.com/store/apps/details?id=com.kohlewrrk.lockclean). Not sure how it'll play with LG though.
Lock Clean Substratum: https://play.google.com/store/apps/details?id=com.kohlewrrk.lockclean&hl=en
If you have substratum, there is a theme to hide/disable them. LockClean [Substratum]
Lock screen and quick settings
Nova launcher prime
Delta icons
Stock clock widget
Ubiquity media widget
Substratum themes
If you're rooted then install Substratum and this https://play.google.com/store/apps/details?id=com.kohlewrrk.lockclean