Unable to upgrade my 2011 iMac to El Capitan

The OS X 10.11 version shown in the footer is El Capitan.

You cannot delete the running partition. If you were booted into Recovery when you tried that deletion (and only saw one storage device and its partitions in Disk Utility), then you may not have a working hard disk.

If the Mac might have hardware problems, try booting diagnostics:

Use Apple Diagnostics to test your Mac - Apple Support

The three iMac models from 2011 can all get to macOS 10.13 High Sierra.

I’d then try booting Recovery, and using Option-Command-R (and not Command-R) to get he latest supported macOS version:

text: How to start up from macOS Recovery - Apple Support

video: https://cdsassets.apple.com/vid/live/hls/7WUAS350/videos/bbda39f7_1748394827.m3u8

This Command-Option-R path works if the Mac involved has once run a middling macOS 10.12 version, or later

If you have another Mac available or can visit an Apple Store, you can bring a USB flash drive and can download and build a bootable installer there, take that to the iMac 2011, and boot and install macOS 10.13 from there. Here is how:

• Create a bootable installer for macOS - Apple Support

If the internal storage has failed, repairing it probably isn’t worth the effort, particularly given an external hard disk or SSD can be used, and can continue to be used after this iMac is retired:

• Use an external SSD as your startup disk … - Apple Community

More…

The directions for unpacking old versions including OS X 10.11 are included in the article: Create a bootable installer for macOS - Apple Support

Once you unpack and install OS X 10.11, you’ll have problems with establishing secure network connections, among other limits. macOS. The latest supported by that Mac, macOS 10.13, is less bad here, but is also bad.

Bad? These are old versions: macOS 10.13 is from 2017, and OS X 10.11 from 2015. Some apps and sites are now requiring users to perform manual certificate management on macOS 11, which is five versions newer than OS X 10.11. The current Microsoft Office apps won’t go back anywhere near as far as this, either.

Barring some exceedingly special app available only on OS X 10.11, I’d again suggest loading the newest available for this Mac: macOS 10.13. Not OS X 10.11.

Kitacode wrote:

• * I also tried to download El Capitan into a usb drive and reboot it , but I was not able to open and it didn’t work

No surprise there.

Apple distributes the El Capitan installer in the form of a .DMG (disk image) file. This is not an image of a bootable installer. What you need to do is to open (mount) it on an old Mac, which already has a working copy of Mac OS X installed, an old Mac that is compatible with El Capitan.

The installer package or application is inside.

If you want to create a USB drive that is a bootable installer, that requires the use of an old Mac and more work, at the command line (Terminal) level.

How to download and install macOS - Apple Support

Once you get to High Sierra (the latest version of the operating system that a 2011 iMac can run), that is behind an App Store link. You pretty much need to be on El Capitan or Sierra before your versions of Safari and the App Store are going to be new enough to access the above Support article and the High Sierra App Store link.

Kitacode wrote:

Mind if I message you ? I didn’t really understand the process but I think I see what you mean just need guidance as I do it . Please ? I wanted to get it ready for my daughter’s birthday and I feel horrible I can’t fix it :(

The directions for unpacking old versions are included in the article: Create a bootable installer for macOS - Apple Support

Once you unpack and install OS X 10.11, you’ll have problems with establishing secure network connections, among other limits. macOS. macOS 10.13 is less bad here, but getting bad.