I used the desktop version in 2022 and want to use the but mistakenly bought an acivation code for the online version for 2023. Can I exchange it ?

You can get a refund for the one you don't want and then purchase the one you do. If you bought TurboTax from a 3rd party retailer, please use the form on this FAQ to request a refund: https://turbotax.community.intuit.ca/community/after-you-file-questions/help/how-do-i-get-a-refund-for-a-turbotax-product/00/873559