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Suppose the following:

+ MCC-LIDAR software is installed in `C:\Program Files (x86)`.
+ Input .las files are stored in `C:\test\input`.
+ Outputs (also with extension .las) are going to be stored in `C:\test\output`.   

The first alternative is an improved version from K.B's code from your [sourceforge link][1]:

    PATH="C:\Program Files (x86)\MCC-LIDAR 2.1\bin";%PATH%
    FOR %%W IN (C:\test\input\*.las) DO (
    mcc-lidar %%W C:\test\output\%%~NXW -s 0.5 -t 0.07
    )
    PAUSE

Here is a brief explanation:

    PATH="C:\Program Files (x86)\MCC-LIDAR 2.1\bin";%PATH%

Maps the MCC-LiDAR software in the system's account Environment Variables, so the `mcc-lidar.exe` program can be recognized.

    FOR %%W IN (C:\test\input\*.las) DO (

Do something with all (*) .las files in `C:\test\input\`. Since it is a `for` loop 'something' is done file by file.

    mcc-lidar %%W C:\test\output\%%~NXW -s 0.5 -t 0.07

At each step in the loop, apply the mcc-lidar.exe tool to a .las file and save it with the same name in folder `C:\test\output\`. What makes it to be saved with the same name are the modifiers `~NX` (~Name and ~eXtension, respectively) appended to variable `%%W`. For example `%%W` is `C:\test\input\data1.las` and `%%~NXW` is `data1.las`.

    )

The close bracket ends the loop.

Another alternative, can be used when one has some sort of index number in the input filename. For example: data1.las, data2.las, ..., data6.las, etc.

Then, use the following code:

    PATH="C:\Program Files (x86)\MCC-LIDAR 2.1\bin";%PATH%
    FOR /L %%W IN (1,1,6) DO (
    mcc-lidar C:\test\input\data%%W.las C:\test\output\data%%W.las -s 0.5 -t 0.07
    )
    PAUSE

The code explanation is in https://gis.stackexchange.com/questions/150294/clipping-las-data-with-multiple-shapefiles/150502#150502.

-------------------------------
If your final goal is to build a DEM, then take a look at a related post:  

https://gis.stackexchange.com/questions/101786/determining-bare-earth-dem-from-unclassified-las-file/108342#108342

[1]:https://sourceforge.net/p/mcclidar/discussion/961944/thread/74cce518/
[2]:https://stackoverflow.com/questions/8648178/getting-substring-of-a-token-in-for-loop/8656232#8656232