To display the current version of Linux (kernel) running on your system, run this command.
# uname -sr
You can list all kernel images installed on your system like this.
# rpm -q kernel
kernel-3.10.0-229.el7.x86_64
kernel-3.10.0-229.14.1.el7.x86_64
kernel-3.10.0-327.3.1.el7.x86_64
kernel-3.10.0-327.10.1.el7.x86_64
One of these utilities is package-cleanup which you can use to delete old kernel as shown below, the count flag is used to specify the number of kernels you want to leave on the system.
# package-cleanup –oldkernels –count=2