How to Format Dates in a Rollup field with multiple dates

[Scribbles_]

Hi everyone,
I've been searching airtable forums for hours yet I can't find a solution that clearly explains what I need to do to achieve my desired results. There are different answers talking about using MIN() or something other formula, but I can't get it to work for me.

I have a lookup field that pulls date entries from another table, but there are many duplicate entries I can't remove.
So I used ARRAYJOIN(ARRAYUNIQUE(values), '\n') in the column beside it to rollup the fields and finally remove the duplicate entries. The problem is there are times attached to all entries as "T00:00:00.000Z" and all 
I want is the date part. For the life of me I can' figure out a way to get rid of them. Is there a way to achieve this result somehow? or to Format the dates?
Any help explaining what I need to do exactly would be helpful, thank you.

[kuovonne · Accepted solution]

In the linked table, have a formula field with DATETIME_FORMAT() to convert the date field to a text string. Then roll up the formula field.

[Scribbles_]

Hi Kuovonne! 
I implemented it and finally got what I wanted.

The linked table:

The result:
I used this to rollup the fields like this

ARRAYJOIN(ARRAYUNIQUE(values), '\n')

Thank you for your answer.