I usually review my fb apps once a year, today was that day and I found out that due to changes in fb policies, most of the fb apps were no more working, but those were still present in my account and had access to my personal information.
Personal information can be sold in good price to several advertisement companies and can be misused by hacking companies thus it is very important to delete those apps from your fb account. Upon my review, I deleted around 40 apps, which were close to half of the total apps which had access to my account.
I would highly recommend you to review apps which have access to your fb account and all those apps you don't use regularly or which are not from famous companies, you should delete them.
The procedure of deleting fb apps is given in the following links: