Unfortunately, there is no formula way to result in a truly blank cell, "" is the best formulas can offer.
I dislike ISBLANK because it will not see cells that only have "" as blanks. Instead I prefer COUNTBLANK, which will count "" as blank, so basically =COUNTBLANK(C1)>0 means that C1 is blank or has "".
If you need to remove blank cells in a column, I would recommend filtering on the column for blanks, then selecting the resulting cells and pressing Del. After which you can remove the filter.