Clear massive system data file on LG G3 I have somehow run out of space on my LG G3. Under storage under Misc I see have a 6.34GB System Data file.

I tried dialling *#9900# as suggested here in order to delete the dumpstate/logcat but when I dial *#9900# it tells me it's an invalid MMI code. http://androidforums.com/threads/low-on-space-system-data-huge.278837/

Note that my phone is not rooted. I can get to the hidden diagnostic menu using the international code shown here, i.e. 3845#*855#, however I can't see any menu items that look like they might clear that system file. 

Any ideas?
This doesn't work on my LG G4 either, and it looks like it's a feature that's available only on certain manufacturers (maybe only Samsung?) rather than all Androids:

How to delete dumpstate/logcat on Moto E

Clearing logcat on HTC one X

As you probably know from reading around, you cannot delete these files using a normal app unless you have root access. The only way to do it is with the OS (which I guess always has root access).

I went to Settings &gt; Storage &amp; USB &gt; Internal Storage and tried clearing cached data, but this didn't seem to do the trick.  (In particular, it didn't effect the size of the mysterious "system data" block that the app DiskUsage identifies and which apparently includes these logcat files.) Settings &gt; Smart cleaning also didn't give access to anything that large.

Wasn't able to solve this.