Looking at my database I see that the xconfig table is huge and contains a majority of "notifications" (k=notifications)

I have a very very large amount (312731) of :

a:1:{s:6: "notice";a:1:{s:13: "notifications";a:1:{i:0;s:21: "Access denied.<br>
";}}}

Access denied is in French in my recordings.

Is it normal for this to accumulate like this ? Can I delete these notifications ?

Thank you for your answers.