@Vitalikssssss this is SO helpful!! Thanks very much! At first I deleted the "left" and "10" because I didn't understand their purpose, but now I get it For anyone wondering, here's an explanation for why it's useful:
The "LEFT" at the start of the formula gives instruction to only keep the left side of whatever is contained in the brackets that follow, and the "10" gives instruction to keep the first 10 characters (to the left, in this case; you can also use "right" in other cases). So you have year (4 characters), plus month (2 characters) plus day (2 characters) plus 2 forward slashes: ex. "2018/03/22", and that's a total of 10 characters. If you didn't limit the date to 10 characters, the time would be included as well.
In case anyone wants the time included in the date-turned-string, just remove the "LEFT(" and the ",10)" from Vitalikssssss's answer above. And if you want only the time, use "right" instead of "left" and replace 10 with the number of time characters (don't forget to include ":" as part of your character count).