@meechon ...
The answer to these, and many pore questions you'll be asking soon, are in the Tutorials, many of which can be found here...
MV Tutorials ...
... but to answer your question directly...
You don't actually have the Character Event go away, simply change aspect. An NPC (Non-Plyer Character...) Event could have a Page 1 with the required Sprite, but also a Page 2 with no Sprite at all, but with a Condition set to a Switch (Choose a suitable name, such as 'Char_Beaten'...). Have the Switch turn On when the NPC is beaten, so that Page 2 becomes active, and the Event becomes invisible. Have the Priority of the Page 2 set to 'Beneath' and it'll be as good as gone..! Try it..?
As for the other Event: the same technique will apply. Have a Page 2 dependant on that same Switch, with no Sprite, and there it is... Gone..!
Does this help you at all..?