How to remove span from rewrite result in a field view?
You will need to click on the fields you excluded (one by one), click on Style settings and select Customize field HTML. Then select -None- under HTML Element. You may need to do this for Customize label and Customize wrapper. Click Apply. Don't forget to click Save.



EDIT: Since you have now clarified that you are using Views Fieldsets (and for next time, be sure to provide ALL details about your problem!), I believe you will need to override the default tpl.php file for the Views Fieldset fields. 

Views Fieldset provides default tpl.php files inside the template folder inside the module folder (usually found in /sites/all/modules/views_fieldset. You need to copy the content of that file, save it in your theme's template folder and modify it. Follow the steps in this general tutorial (you will need to adapt it to your problem) to override the default template for Views Fieldset fields.  Good luck.