What activities should be undertaken after uninstallation of SpurIT Wholesale Pricing in Vintage themes?

When you uninstall the application in the Shopify admin panel, the theme will still contain code snippets from the application.

This is typical for all Shopify applications, because after you uninstall the application from your store it no longer has the rights to restore all the previous changes it made to the theme.

Open Themes section on the admin panel of your web store (Online Store → Themes);
Find Theme from the list which will be used with our installed app.
Click Actions → Edit Code.
Find theme.liquid file and delete the short 3 lines block which starts from the line:

<!-- spurit_wsmm-added -->
{% render 'spurit_wsmm-theme-snippet' %}

and end with the line:

(optional step) in the Snippets section delete the file spurit_wsmm-theme-snippet.liquid
Remove the file theme-without-spurit_wsmm.liquid located in Layout section.
Remove the customers/register-without-spurit_wsmm.liquid and cart.spurit-items-collections.liquid located in Templates section.