How Do I remove The sitename from all page titles ?

After switching to a new different WordPress theme, Google started adding the sitename to all my pages in the search results. Even when leaving the sitename area blank , Google adds the Homepage title next to every page title. example “Page Title – Sitename” or “page title – homepage title”. I only want the Page title to show.

Currently I am using the yoast seo plugin and tried removing removing “%%sep%% %%sitename%%” in the yoast settings, but it didnt work.

Please help