I just changed my single user home directory to "/", can I return back? While deleting another user account on System Preferences, I changed the home directory for the primary user (System Preferences>Users and Groups>Users>Advanced Settings) to "/", because I already have done in the past two partitions of the same disk for two users, to separate applications and documents for both users, then I updated the second user to Catalina, and I moved both users to only one partition. Now after deleting the other user account (older version) while moving the applications back to the other partition applications folder and setting up the home directory to the actual partition (system preferences>user advanced settings) I realized that the apps I been recently moving to the dock didn't show-up (it was routed to the other partition I guess), so Instead of routing the home directory of the user to the actual partition I choosed "/" thinking that the directory routing flow could be actualized by the computer, instead of realizing that in this way the user was left out of both partitions.
Unless you have very specific technical reasons for doing so, then modifying MacOS's installation is unnecessary and may cause problems. There's no need to make separate partitions for users, or to move the default location of User accounts. 

As you have found out, the root level is read only in Catalina, and any non-OS files and folders will be moved to /Users/Shared when the OS is installed. 

If I were you, I would backup your data, boot to Recovery, remove any partitions, reinstall the OS, create a new user account, and then restore your data and apps to the correct intended locations.