See Determine the package name of your app to get the package name of the concerned app and use adb shell to execute these commands:
adb shell su pm disable PACKAGE # disables the app and hides it in Settings -> Applications pm hide PACKAGE # alternative; for Android Lollipop and above cmd package suspend PACKAGE # alternative; package remains visible in Launcher and Settings app but cannot be used; a feature of Device Administration
PACKAGE refers to package name of the app
To reinstate the app, replace disable with enable, hide with unhide, and suspend with unsuspend in the said command and execute it with root privilege.
If you've Android KitKat or above and do not have root access, use adb in PC to execute this command:
adb shell pm block PACKAGE # for Android KitKat adb shell pm hide PACKAGE # for Android Lollipop only adb shell pm disable-user PACKAGE # alternative to `pm hide`; for Android Lollipop and above; this works just like disabling an app through Settings app
To reinstate the app:
adb shell pm unblock PACKAGE # for Android KitKat adb shell pm unhide PACKAGE # for Android Lollipop and only if you used `pm hide` earlier adb shell pm enable PACKAGE # for Android Lollipop and above
Changes would take place immediately.