The intermittent horn (beeping sound) that you hear is the Take Off configuration warning horn. It is there to warn pilots that either: flaps are not set for take-off, the park brake is set, the spoilers are up (the speedbrake lever is not fully down), or the stabiliser trim is not in the "green band" (a setting for take-off).
The horn will only sound when the poweer is in the region of 60-70% N1 (it's actually triggered by thrust lever angle IIRC). This is far more than needed to taxi in after landing, where 30% should be more than enough, and is well below the threshold for setting off the config. warning.
Bottom line: after landing, taxi using idle to 30% power and that should stop the noise.
Hope that helps.