Disposal of a Corpus Delicti, if you want to know, isn't as easy as you'd think.  The stink of decomposing meat is the biggest problem.  Time, forensic traces, bone-digging dogs, dental records, hair fragments.

Throw a body in a lake and the decomposition of its cells will fill its stomach and lungs with gas, bringing it to the surface.  You have to stab it once over each pec and twice in the guts.  Like letting air out of a tyre.

Same for burial.  Most shallow-graves don't work for shit because the body swells like a mini hillock.  Like midget subduction.  Bonsai volcanoes.

Throw a body in the sea and piece-by-piece its bits will come loose.  You've got to make sure it's weighted all over, bound head-to-foot, or there'll be fingers and toes washed up on the beach.

Cue fingerprints, DNA testing, undernail skin-fragment analysis.

If you have enough time, and no visitors, doing it piece-by-piece down the plughole is best.  For this you'll need:

A standard hacksaw, with two or three replacement blades.

A mallet, for ball joints and thick bone..

Two dozen large freezer bags, sealable.

A large freezer.

Five or six 2 litre bottles of industrial-strength bleach, to cleanse your pipes after every discharge.

A powerful food processor, with replacement blades. 

A lot of replacement blades.

A lot of patience.

Rubber or plastic sheets, to prevent drips and sprays.

More replacement blades.

Approximately two weeks.