Removing a sidebar

Hi
am using Gardening Theme WP 8 and having a few issues with the post pages layout. I cannot seem to find an option for these pages to only have the one sidebar, sidebar 2. The site displays perfectly on the static home page but when you click on the posts you get an extra ‘search menu’ and ‘uncategorised’ one, seems very odd and annoying and hence I would like to know how I could remove them both, here’s the link: https://nambourcommunitygardens.com.au/?p=342
I don’t however want to change the coding in ‘sidebar 1 php’ as the template is gr8 and I could stuff it up as don’t know what I am really doing in this area.
Any advice would be appreciated, thank you.
M