We couldn't parse the input provided as a DateTime value..

Nimai123 , refer is these can help

https://community.powerbi.com/t5/Service/We-couldn-t-parse-the-input-provided-as-a-Date-value/m-p/73783

https://community.powerbi.com/t5/Desktop/DataFormat-Error-We-couldn-t-parse-the-input-provided-as-a-Date/m-p/864740

Check the exact error on power query

handle error in power query
https://www.youtube.com/watch?v=OE6DPmKqN7s
https://www.youtube.com/watch?v=9-Lag0VOiTs

You should be able to convert text formatted date's to dateTime without any issue so there is something trong with the text. It might be that it's the wrong delimiters or that there are other blankspaces present in the date. If you provide an image of the dates I might be able to see if there are any issues directly. 

Otherwise what you can do if you really can't get it to work is splitting the text column up in year, month and date and use this custom column to create a date: (Make sure that all three columns are formatted to whole number)

#date([Year],[Month],[Date]) as date

Br,
J