[webreac]

rm is a good start, but you also need to ensure the disks are not sold to anyone.

[bayindirh]

When you enable TRIM, it's zeroed automatically, so you're 99% there with an rm.

[bestham]

No, the point of enabling TRIM is to not induce further write amplification. The zeroing is deferred until the block that is trimmed is over written. It is released from the indefinite garbage collection that exists in a pure SSD implementation that does not know what blocks are important. Some firmwares answers with nothing when requesting a TRIMed block. Others answer with the content of the block as it is on NAND. Either way, the bits are most likely still on NAND.