One of the primary challenges when trying re-purpose existing storage devices is ensuring that all data and existing partitions have been completely removed. Often times, customers end up resorting to third-party tools like GParted which requires you to boot your server into the LiveCD before you can remove the existing partitions. This is less than ideal, especially if you need to perform this operation across multiple systems.
For customers who wish to re-purpose their existing storage devices for other use, including VSAN, there is now a new UI option in the vSphere Web Client introduced in vSphere 6.0 Update 1 to help assist with this procedure. I had not seen anyone talk about this feature yet and figure I would share some details as this is something I have heard customers ask for in the past. You can find this new option (icon with disk and eraser) by clicking onto a specific ESXi host and then selecting the Manage->Storage Adapters and then highlighting the specific storage device you wish to erase as seen in the screenshot below.
Once the erase partition icon or action is selected, you will then be presented with a summary of the existing partitions on the disk and then prompted to confirm that you wish to delete ALL partitions on the disk.
For those of you who are interested from an Automation standpoint, this UI operation actually makes use of an existing vSphere API that has been for quite some time called updateDiskPartitions() under the StorageSystem manager of an ESXi host. To erase all partitions, you simply pass in an empty spec to the API method.
In addition, I also want to quickly mention that you will also have the ability to edit and erase existing disk partitions using the ESXi Embedded Host Client Fling which will be available in a future update. Below is a quick screenshot on what that would look like.