How to convert a date to a string in Google Sheet

You can use the TEXT function.

=Text(cellReference, "mm-dd-yyyy")

=TEXT(now(),"yyyy-MM-dd hh:mm:ss")

This cell is now a string.

Use the TEXTJOIN function. Give an empty delimiter, TRUE for the ignore empty, the referenced cell as text1, and don't supply anything for text2.

=TEXTJOIN("",TRUE,A1)

Done.

1. copy the column to another column
2. select the copied column
3. go to menu 'Format' --> 'Number' --> 'Plain text'