Apps in Windows 8x can retrieve data from your account, including your name and picture. How this information is used depends entirely on the app. You will find such information on the privacy statements for each app but, if you do not want any app to have access to this kind of information, you can easily block the access to them all. Windows 8 and Windows 8.1 have this setting in different places but it does the same for both. Note that if you disable this feature, some apps that need personalized info to work will be buggy.
Go to PC settings by pressing WinKey + I and then clicking on “Change PC settings”. Once you are there, click on the Privacy menu and disable the setting that says “Let apps use my name and account picture”
Open PC settings with the way I described above and click on the Privacy menu. Make sure you are in the General tab and disable the setting that says “Let apps access my name, picture and other account info”