I am comparatively new to PCB layout,so forgive me if my questions look silly to you !
So, here I made a simple circuit demonstrating V=IR
and then replaced the resistor with a capacitor.

Now , in the corresponding PCB layout, only the component got replaced ,which is alright. I tried to delete the previous tracks and connection and some leftover holes(I guess those are holes only), but I am unable to do so.And I don't even know what that black thing symbolizes(inside the hole). I am not able to delete the blue track and the hole and I can't even select it.

https://easyeda.com/editor#id=78edbbe3875548fa92ce9517d7fe69cc|dee766f93c394e36a1edd9f2b4b999ea|1b1740dad01643a59744ba56035e4192|29c4072671d54107be747ad893522937

By the way, the actual situation is much more complex than a simple V=IR circuit. It's a customized PCB with hundreds of components in it,which I cannot share due to company policy(obvious).