I'm completely new to using a Mac, and recently installed UBUNTU by following some YouTube videos and it worked fine. I added 50GB for the UBUNTU partition and 8GB for the SWAP partition. I now want to restore my 58 GB back to the MacOS partition and want to delete UBUNTU. Can someone please give me a detailed step-by-step process on how to delete UBUNTU and reFInd and retrieve my MacOS back completely. Since it's a new Mac, I'm not worried about data loss and there are no important files. Kindly help please. Thank you so much in advance. I couldn't be more grateful 
