Help with erase and clean instal of catalina

[inscrewtable]

I just had to do an erase and install on the gf's iMac that got stuck in a boot loop while installing. What I thought was the right way, was not the right way and after dealing with some apple techs, who also thought I was doing it the right way but was in fact the wrong wa, I ended up having a senior advisor walked me though it which involved installing it via internet recovery onto an external drive in order to boot from that and erase the internal fusion drive, then erasing and reformatting the internal imac drive twice. It was incredibly confusing but the take away message was that with the latest catalina it's apparently no possible to make boot drive onto a usb stick. It may have been more complicated because I was trying to recover files.

However I'm now wanting to do a clean install on my rMBP without needing to recover anything as I have backed up my entire home folder. The mac has been taking 50 seconds to boot instead of 12 seconds when it was new, so I want to do a complete erase and install

Because I'm not trying to recover anything the above instructions are redundant but I'm also not sure of the best way to completely erase my SSD on the MB so I can do a clean install.

It is possible to use internet recovery to completely erase my SSD and install a clean copy of catalina onto the mbp, or do I have to somehow make an external boot drive on another HD to use disk utility to erase my SSD.

thanks.

 

[Red Menace]

I've used an USB flash drive to create a bootable installer for Catalina with no issues. You can boot from that, erase/format the internal drive, and install a clean copy.

 

[Fishrrman]

OP:
You could try this:

First -- BACK UP the ENTIRE internal drive to a cloned backup, created with either CarbonCopyCloner or SuperDuper. Both of these apps are FREE to download and use for 30 days, so doing this costs you nothing.
Once you do this, you're now fully backed-up and can wipe the internal drive.

I strongly advise you NOT to erase the internal drive UNLESS you have a bootable backup!

Now, boot to INTERNET recovery (NOT "the recovery partition):
command-OPTION-R

When you get to the utilities menu, open disk utility.
Go to the "view" menu and choose "show all devices" (VERY important that you do this).
Next, on the left, click on the topmost line (represents your internal hard drive).
Click the erase button and choose APFS with GUID partition format.

Once erased, quit disk utility and open the OS installer.
Click through and get the install going. It may involve one or more reboots, perhaps a period where the Mac's screen goes dark for a minute or two, and one or more "progress bars". Be patient.
When done, you should see the setup screen ("choose your language").
Start clicking through to set up.

Now you have a decision to make:
Do you want to use setup assistant to restore your data from the backup?
If yes, wait until setup assistant asks if you wish to migrate from another drive.
YES, you want to do this, so...
Connect the cloned backup and give setup assistant some time to "digest" everything. It may take a few minutes with little feedback, so be patient.

Setup assistant will present you with a checklist of stuff to migrate.
It's up to you what to choose, but I'd choose everything and "let 'er go".

When done, you should see your login screen, just as before.
So... log in and look around...