I don't see that functionality when N1MM launches WSJTx. I am running WSJTx from inside N1MM. N1MM knows about the WSJTx contacts but the reverse is not true. I do a File Open log directory and erase WSJTx logs there. Once the WSJTx logs are erased everything is new. It's still possible to get a dup if you worked them on phone and logged directly to N1MM as WSJTx does not know about N1MM contacts, it only knows the contacts it made.
7 3 Bob
N2SCJ
-----Original Message-----
From: main@WSJTX.groups.io [mailto:main@WSJTX.groups.io] On Behalf Of Jim Brown
Sent: Saturday, June 12, 2021 6:20 PM
To: main@WSJTX.groups.io
Subject: Re: [WSJTX] Where to delete previously worked station data #ContestMode #logging #FT8 #logging
On 6/12/2021 12:54 PM, Joe Barkley wrote:

Hi all I am trying to eliminate stations from being grayed out  in the
decode window during the contest which I assume comes from the
station's I have previously worked. It would be nice to lose that data
during the contest but then retrieve it afterwards. I have been trying
by renaming the log but that doesn't seem to do it. Any ideas?

Use a Contest Logger, like N1MM (free) or WriteLog (not free). An important thing that they do is keep track of dupes.
73, Jim K9YC