I was bought Acer Aspire E5 576-G recently and its beeping when plug/unplug charger i searched about disable Beeping but its not about Beeping.
So here is how to solve it ;
Right-click the speaker icon on your system tray and select "Open Volume Mixer"
then u should see Speakers and System Sounds volume bar then plug your charger in.
After beep sound come there , Realtek Audio Manager should appear there and click this speaker button
under the Realtek Audio Manager and its Muted now. Problem is solved for me. Hope it helps to someone who has that issue.
Also it looks like Realtek Audio driver's issue and idk why Acer isnt fixes that.
[Edited the title to add model name ]