How can I merge two users on my iMac?

The following may be more to your liking. I am assuming your "main Mac id" is the admin account.

1. From your main account open finder and locate the user account for your pc files. (Macintosh HD/users/pcfiles)
2. Right or control click on that folder and select Get Info.
3. Under sharing and permissions click on the lock icon to unlock permissions. Give admin password when asked.
4. Once unlocked, click on the + button and add your main id to the user names
5. Set your permissions to Read & Write.
6. Click on the gear icon and make your main id the "owner" of the folder.
7. Click on the gear again and apply to enclosed items.
8. Click on the lock icon to re-lock the folder.

Your main id now owns the pc files. You should be able to move files or folders to your main id file structure (no need to copy) or just access them as is. You could import directly into iTunes or iPhoto etc.

Use the Shared folder on the root "/" directory to copy files into,

log into the other user and select the contents of what's inside the shared folder (not the folder itself) and Get info, change the permissions on the bottom to the second account and "Apply to enclosed items"

before moving them into your folder or importing them into programs like iTunes and iPhoto.

https://discussions.apple.com/community/notebooks/macbook_pro?view=documents

I had the same problem and used this method to combine two of my logins (work & home). I just wanted everything under my home account for simplicity sake. I noticed though, as the bar said 'Applying privileges' that the size of the folder went from about 6 gigs to over 40 Gb. Is this normal?

This is helpful, THANK YOU!

Thanks, Dansyacht! I recently replaced my MacBook Air with a new MacBook Pro. I gave the Air to my wife & set up a user ID for her. She was unable to update apps, etc., until I followed your step-by-step instructions that worked like a charm! Other instructions found were telling me I would need to do a clean reinstall of the OS and set everything up from there. Your method really helped me solve the problem with MUCH less effort! Thanks again!