format disk Time Machine

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If you want and you don't need the data of your old backups, you can format the external drive. To do it, use Disk Utility.

Open Disk Utility (in /Applications/Utilites) and choose your external drive in the sidebar. Then, go to Erase tab and erase the drive. You may need to set up Time Machine again, so open System Preferences > Time Machine > Select Disk, and choose your external drive again. It will start making backups

Open Disk Utility in your Appplications folder

Select the disk go to Erase and click the erases button

Time Machine will reformat the disk anyway before first use.

System Preference > Time Machine and select the disk

If you need help erasing the drive, see > http://pondini.org/OSX/DU1.html

@mende1 or @Axeman1020, I have a similar problem as described above. But mine is complicated further by an OS problem. When I go into my utilities folder the iDisk utility has a strikethrough icon on it and I get the following message when I try to open it:

You can't open the application "iDisk Utility" because PowerPC applications are no longer supported.

I have a 2.8GHz i7 iMac running OSX 10.9.2. Any advice???

Mavericks does not support PowerPC applications.

In addition, Apple discontinued MobileMe on June 30, 2012 and iDisk is no longer available.

Apple gave MobileMe subscribers just under a year to migrate to iCloud before closing MobileMe permanently.

Thanks for the prompt response @Axeman1020, but that doesn't help me. If the iDisk Utility is no longer available as a core utility within OSX, what is the best alternative?

I can manually go into the hard drive and delete files, but I don't want to corrupt this device by going about it wrong.

Here's my situation: I ran into a technical fault on my iMac this Spring that required warranty service. When I got my iMac back I had to restore from my Time Machine backup. So far, no problem...

But now, my iMac doesn't recognize the backups on the Time Capsule drive for what they are and essentially I'm told that my 2TB Time Capsule only has 325 GB of the 2TB available. As my iMac is fine in its current state, I can afford to just reformat the drive on the Time Capsule and start over. But I don't want to screw anything up now that the Utlity that I know (iDisk) is no longer supported.

Can you point me in the right direction?

I think you misunderstood our advice.

What you want is Disk Utility not iDisk.

Disk Utility is in /Applications/Utilites or hold the Command key and tap the spacebar to open Spotlight and begin typing Disk Utility.

Disk Utility works only if you have an external HD connected via USB. My Time Machine uses a Time Capsule setup so I had to wipe it via Airport utility.

I have the same question.

A mac Pro with 10.10.4

Have doen a complete bare bones rebuild and instal, and copied all data over to new boot nd user folders, manually.

No i have a TM HDD with old data to re format/ re partition.

Time machine is Off

But Diskk Utility won't re partition or erase..Options for that are greyed out.

I am logged in as a Admin.

Did wonder about enabling 'Root' but wondered if there are any other options