clicks can be difficult if they are sample 'trailing-clicks'. Clicks comes from a sample not having lead-in / lead-out to silence. Drum-samples, like a kick would not work if it did not 'fade out' to silence -thats how a drum 'works'..
So most likely your clicks are 'lead-in', and those can be fixed very simple.
Open the Env/LFO/Filter tab
Set the AMT (amount) tp right max
Loop-replay your sample and add ATT (attack) and listen for the clicks to disapear. You normally dont want to 'push' the attack too far, that alter the sample (but that can be super somtimes:) -just listen for the clicks to disapear and then save your instrument.
Trailing clicks however can be a drag.. some can be eliminated with fiddleling with both or either of DEC / REL, but often the only real solution is to edit the sample in a wave-edit-program like audacity (free and recomended)
-and btw read this -and the est of the wiki :p
http://lmms.sourceforge.net/wiki/index. ... Filter_tab