//settings:
openTag    = "<span";
closingTag = "</span";

//get current line number:
yLine = document.selection.GetActivePointY( eePosLogical );

//get line content:
str   = document.GetLine( yLine );

//search for occurrences in this line:
openTagPos    = str.indexOf(openTag);
closingTagPos = str.indexOf(closingTag);

//if an closing tag is found:
if(closingTagPos > -1){
	//if no opening tag is found at all 
	//OR 
	//if closing tag is found before the first opening tag
	if(openTagPos == -1 || (closingTagPos < openTagPos)){
		//<here find first closing tag and remove it>
		alert(closingTag + " to delete found");
	}else{
		//nothing to do in this line. This code can be removed.
		alert("lines is ok");
	}
}else{
	//nothing to do in this line. This code can be removed.
	alert("not found " + closingTag);
}