I started doing the taxes on TurboTax, however, I would like to delete/cancel acct. since I filed an extension and when ready to file, we will not be using turbo tax.

You can try to clear you return but you can not delete your account. How to delete/clear your Online return
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-online/00/26444

You can call in and ask them to deactivate it. Contact Customer Service at
https://support.turbotax.intuit.com/contact/

And I found this article...To delete your info 
https://ttlc.intuit.com/turbotax-support/en-us/help-article/accounting-bookkeeping/request-delete-download-intuit-data/L9pTFjwSB_US_en_US?uid=m1qr3f3k