I use this plugin a LOT, especially for checking lyrics for intriguing tracks playing on radio streams

As such, the log file it creates grows and grows, as it adds to vs. replaces itself as the plugin is used. I use this simple script in a batch file to delete it, placing a shortcut to the .bat in my Windows startup folder for set-it-and-forget-it mode:
cd C:\MusicBee\AppData\mb_LyricsReloaded
del mb_LyricsReloaded.log
The path reflects the Portable install options for MusicBee I have chosen, change it to reflect yours.
Likewise, the lyrics themselves add up in a series of numbered subfolders and .dat files in the MusicBee\Appdata\InternalCache\Lyrics folder. A batch (.bat) file with this code takes care of that in the same way as the log:
@ECHO OFF
Set dir="c:\MusicBee\AppData\InternalCache\Lyrics"
Echo Deleting all files from %dir%
del %dir%\* /F /Q
Echo Deleting all folders from %dir%
for /d %%p in (%dir%\*) Do rd /Q /S "%%p"
@echo Folder deleted.
exit
As with the log file example, change the "Set dir=" path to match yours. Now get back to grabbing lyrics!