Best way to wipe data partition on SSD?

There is also a little front end for it. Not necessary, the command is simple enough.

Thanks @SIW2, very useful link.

I already have ccleaner just never realised it could wipe free space too!

The tool supplied by the SSD manufacturer is the best way because it's the only way to be sure, it uses the ATA Secure Erase command to wipe the entire SSD. This command can also be triggered without using the manufacturer's tool, e.g. under Linux if the SSD is so old and/or exotic that the manufacturer doesn't supply a tool. If the SSD is Samsung, in Samsung Magician there's a Secure Erase option (listed under Data Management). All the other methods that have been discussed in this thread are not guaranteed to be secure, as all SSDs use what's called factory overprovisioning so writing new data to the SSD does not in any way imply that data previously written will be erased (and neither does the TRIM command, for that matter...). In addition to factory overprovisioning, it also is possible that the SSD in question uses the combination of data compression and dynamic overprovisioning, in which case the entropy of the stored data is also among determining factors as for which pages in the NAND are truly getting erased prior to writing new data, during garbage collection or during TRIM. Whereas the ATA standard officially states that overwriting the data is a mandatory step during ATA Secure Erase so, technically, any SSD that doesn't do this is not an ATA compliant device and would therefore be illegal to be adverstised as ATA compliant. Your safest bet is to assume that all the manufacturers want their SSDs to be ATA compliant because nobody buys SSDs that aren't, and they know they'd catch serious hell if it later turned out they'd been faking ATA compliance so they're not going to risk it.

Thanks all for the advice.
After waiting ten days for Dell to get round to swapping the disk out I now have a functioning laptop again.
I do have another issue now but that relates to a tutorial so I'll post there.
Cheers
Rob