Yes, you can edit, replace, delete or do whatever you want to your books on Okadabooks.
This one is very easy for both uploaded Epubs and those that used the Copy-paste method... follow the steps in the screenshots below


Sign in to the account you uploaded the book with...
Click on the dropdown close to your profile name
Click on MY MY WORKSA page will load up with all your published works

If you used the Copy-paste method, Click on the Pencil Icon in front of the book you would like to Edit... The edit page will open...

If you initially uploaded an Epub, Click On the X icon to delete the old book. You might get a warning, ignore it and don't close the page... 

Click on the UPLOAD EPUB option to upload your new copy

After it's been uploaded... Click On REPUBLISH

That's all. If you encounter any errors, leave a comment below. You can also delete or unpublish your books with this option.

You can also watch the video below to understand how to change your book's price and other details