How to remove facebook comment box from sidebar

hi
I am new to wordpress actually I am trying to remove facebook comment box from sidebar
right now I am using “Facebook” plugin for commenting and also using “Social Media Mashup” plugin in my sidebar
when the both plugin is activated at that Facebook comment box is appearing in my “Social Media Mashup widgets” in sidebar.
I don’t want that comment box in sidebar what do I do.

in Facebook plugin there is is_single() function is use to appear comment box in post.

is there any alternate function for is_single()

thanks in advance

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