Not as such. Word's drawing doesn't work the way something like Paint works.
You can undo the last action you did (Ctrl+Z), or you can select any
distinct/separate part of the drawing and tap Delete. But, the only way to
effectively "erase" part of an object would be to mask it with something the
same color as the background. This can get very messy.
For the kind of drawing control you want, I would suggest something like
Windows Paint, Paint.Net (free open source program), or one of Adobe's
offerings.
