Also Read: How to add a Colorful Search Box Widget on Blogger
1) From Blogger's dashboard go to Template -> Edit HTML.
2) Simply use the Ctrl+F keyboard shortcut to open up the search box and search for <body>.
3) Now paste the below code just before the <body> tag.
<b:if cond="data:blog.pageType == "index""> <b:if cond="data:blog.searchLabel"> <style> .status-msg-wrap{display:none;} </style> </b:if> </b:if>And press on "Save Template" button.
That's all, now you can check the label page on your blog. If you have done all right you should not see "Showing posts with label" message box anymore.