deleted formulas reappearing

deleted formulas reappearing

I created a column of dates formatted as year-month-day.

The first date was manual but the others were made by '=A1+1' (in A2) and copy pasting.

After doing some editing, I deleted most of the entries in the column using cmd-x (i'm on a mac)

The cells appeared to be blank after this but upon entering data, the cells which had previously refernced teh newly refilled cell became filled. There formula entry appeared not to have been deleted. Only the text?