/etc/yum.repos.d/*.repo. However, each .repo file can and usually have more than one yum repository defined in it, but it is usual that they are all interrelated in a "binary", "sources" and "debug-info", ie. .repo includes the configuration of three interlinked yum repositories. If so just delete the .repo file e.g. rpmfusion-fusion-free.repo, otherwise, be careful to just remove the appropriate sections of the repositories you wish to remove, using a text editor of your preference.
/etc/yum.repos.d/rpmfusion-free.repo
[rpmfusion-free] name=RPM Fusion for Fedora $releasever - Free baseurl=http://download1.rpmfusion.org/free/fedora/releases/$releasever/Everything/$basearch/os/ #mirrorlist=http://mirrors.rpmfusion.org/mirrorlist?repo=free-fedora-$releasever&arch=$basearch enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmfusion-free-fedora [rpmfusion-free-debuginfo] name=RPM Fusion for Fedora $releasever - Free - Debug #baseurl=http://download1.rpmfusion.org/free/fedora/releases/$releasever/Everything/$basearch/debug/ mirrorlist=http://mirrors.rpmfusion.org/mirrorlist?repo=free-fedora-debug-$releasever&arch=$basearch enabled=0 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmfusion-free-fedora [rpmfusion-free-source] name=RPM Fusion for Fedora $releasever - Free - Source #baseurl=http://download1.rpmfusion.org/free/fedora/releases/$releasever/Everything/source/SRPMS/ mirrorlist=http://mirrors.rpmfusion.org/mirrorlist?repo=free-fedora-source-$releasever&arch=$basearch enabled=0 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmfusion-free-fedora