The Fast Save feature in Word saves both the original version of your document and ALL the changes you’ve made to it.
So even though you may have deleted text and graphics—as long as Fast Save is turned on—the file will get larger and larger as it keeps recording every change you’ve made to the file.
In general, it’s recommended that you turn off this option as it leads down a one-way road…
From the Tools menu, select Options and then the Save tab.
Uncheck Allow Fast Saves.