How to delete original partition I have a question regarding deletion of partitions on a Mac.  Due to some performance issues, I decided to start fresh and created a new partition (NewOSX) on the hard drive, to which I have transferred all the data that I need from my old, original partition (MacintoshHD) along with installing an operating system, downloading apps, etc.  I would now like to go ahead and delete the old partition and merge the disk space into my new setup.  I know this isn’t as simple as deleting the newer partition would be, as the minus sign in the disk utility partition menu is greyed out.  

Here is the info of the two partitions that I am referring to:  

Macintosh HD         
Capacity: 119.2 GB        
Used:     47.54 GB         
Device:   disk0s2                     

NewOSX                    
Capacity:  129.35 GB           
Used:      34.69  GB                              
Device:    disk0s4                           


I am wondering if there is (hopefully) a less than super-technical workaround that can accomplish this task.  Thank you. 

Note: Though there is 47 GB still on the old partition (MacintoshHD), I no longer need anything from it and it is ready to be wiped clean.  Also, both partitions are running the “El Capitan” operating system. 

diskutil cs list  
No CoreStorage logical volume groups found 

sudo gpt -r show /dev/disk0  
start            size  index  contents  
          0          1         PMBR  
          1          1         Pri GPT header  
          2         32         Pri GPT table  
         34          6           
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B  
     409640  232811696      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC  
  233221336    1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC  
  234490872  252636720      4  GPT part - 48465300-0000-11AA-AA11-00306543ECAC  
  487127592    1269536      5  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC  
  488397128          7           
  488397135         32         Sec GPT table  
  488397167          1         Sec GPT header  




Update

After having some trouble with Internet Recovery Mode and seeing my system crash a few times during reboot, I decided I didn't want to take any risks and mess around with Recovery HDs at all.  What I ended up doing was wiping Macintosh HD clean, reinstalling the operating system, and then took a few hours to manually transfer data, redo settings, etc., from NewOSX to Macintosh HD.  Then went to disk utility and deleted the NewOSX partition, which of course is a simple procedure.  Thanks for the assistance, wish I had realized the simple solution earlier.
Just because you can, doesn't mean you should.

Why not just back up your data and wipe the entire partition? I suppose if you want to learn how to move things around and you already have a bootable backup that you've tested, the plan of action you propose might be an interesting learning experience.

For anyone that's not sure they can pull off this, Apple posts supported instructions for a wipe and reinstall.


https://support.apple.com/kb/PH18869


It uses the Recovery Partition to perform the wipe. If you don't run caching server to keep fast access to the installer you downloaded, you can make a USB bootable drive to do the deed as well.


https://support.apple.com/en-us/HT201372


These are supported and designed to avoid human errors. Also, it ensures you get a clean partition table with a supported Recovery HD partition for ongoing maintenance and efficient management of OS X.