Modify or delete code through X++

static str 60 addValidateCode(FormName formname, TableId refTableId, FieldId 
refFieldId)
{
    #AOT
    TreeNode    treeNode;
    TreeNode    methodsTreeNode;
    str         oldsource;
    str         newsource;
    str         superString = "super()";
    str         busRuleString;
    str         newMethodName;
    str         newMethodCode;
    ;
    treeNode = TreeNode::findNode(#FormsPath + "\\" + formName);
    treeNode = treeNode.AOTfindChild("Data Sources");
    treeNode = treeNode.AOTfindChild(tableId2Name(refTableId));

    if(refFieldId)
    {
        newMethodName = "validate";
        newMethodCode = "public boolean validate()\n{\n    boolean ret;\n    
;\n    ret = super() && PABusInessRules::CheckRules(element, this," + 
strfmt(' %1',refFieldId) + ");\n\n    return ret;\n}\n";
        //bus rule string is different if applied to a fieldId
        busRuleString = "super() && PABusInessRules::CheckRules(element, 
this," + strfmt(' %1)',refFieldId);
        treeNode = treeNode.AOTfindChild("fields");
        treeNode = treeNode.AOTfindChild(fieldId2Name(refTableId,RefFieldId));
    }
    else
    {
        newMethodName = "validateWrite";
        newMethodCode = "public boolean validateWrite()\n{\n    boolean 
ret;\n    ;\n    ret = super() && PABusInessRules::CheckRules(element, 
this);\n\n    return ret;\n}\n";
        busRuleString = "super() && PABusinessRules::CheckRules(element, 
this)";
    }

    methodsTreeNode = treeNode.AOTfindChild("Methods");
    treeNode = methodsTreeNode.AOTfindChild(newMethodName);

    if(!treeNode)
    {
        methodsTreeNode.AOTadd(newMethodName);
        methodsTreeNode.AOTsave();
        treeNode = methodsTreeNode.AOTfindChild(newMethodName);
        newSource = newMethodCode;
        treeNode.AOTsetSource(newsource,false);
    }
    else
    {
        oldsource = treeNode.AOTgetSource();
        // check if rule already applied
        if(strscan(oldSource,busRuleString,1,strlen(oldSource)) == 0)
        {
            newSource = strReplace(oldsource,superString,busRuleString);  
//new line to be inserted
            treeNode.AOTsetSource(newsource);
        }
    }

    TreeNode = TreeNode::findNode(#FormsPath + "\\" + formName);
    treeNode.AOTcompile();
    treeNode.AOTsave();

    return busRuleString;
}