Transfer Ownership of a Single Document
In the document’s sharing settings:
- Go to the document’s sharing settings
- First make the desired owner an Editor (if they are not already)
- Change their role to Owner
Detailed Instructions are available in the Google support article: Transfer File Ownership
Transfer Ownership of Multiple Documents
From your document list at http://drive.google.com, check the checkbox next to the documents you’d like to transfer, then click the sharing button. As with an individual document, first make your colleague an Editor, and then you will be able to switch their role to Owner as described in the Single Document section above.
To more easily find all files YOU own, use the advanced search in Drive by clicking on the little triangle on the right inside corner of the search box. You will see an option “owned by me”.
You can also create a folder specifically for this purpose, move files into it, then select them all and change ownership.