Yes. You can go into your own "Blocked" list and unblock them. However, this does not remove their block on you . They will remain unable to contact you until they decide to unblock you on their end.
Find the user and select the option to unblock them. How to Unblock Someone on Steam (Web Browser) how to unblock someone steam
Use this method if the person is no longer in your list and you need to see a full directory of everyone you have blocked. Click on your in the top menu and select Profile . Click on Friends in the right-hand sidebar. Select the Blocked Users tab on the left-hand menu. Click the Manage Blocked List button. Check the boxes next to the users you want to unblock. Click Unblock at the bottom of the page. What Happens When You Unblock Someone? They will remain unable to contact you until
Unblocking a user on Steam is a straightforward process that restores their ability to message you, comment on your profile, and see your online status. You can manage this either through your Friends List or your Profile settings. Method 1: Via the Friends List Click on your in the top menu and select Profile
They can once again send you direct messages and invite you to games.
For more detailed troubleshooting, you can visit the official Steam Support page. Steam Friends List - Steam Support