Normal would be to use 'cfdisk' or 'fdisk' to delete the old partition(s) then create a new partition with the desired type. Write the partition table to the device then exit. You should update the partition table by the use of 'partprobe' to update from the changes;
excerpt from 'man partprobe';
partprobe - inform the OS of partition table changes
partprobe [-d] [-s] [devices...]
This manual page documents briefly the partprobe command.
partprobe is a program that informs the operating system kernel of partition table changes, by
requesting that the operating system re-read the partition table.
This program uses short UNIX style options.
-d Don't update the kernel.
-s Show a summary of devices and their partitions.
-h Show summary of options.
-v Show version of program.
You can then format the partition with the filesystem of choice with mkfs;
excerpt 'man mkfs';
mkfs - build a Linux file system SYNOPSIS
mkfs [ -V ] [ -t fstype ] [ fs-options ] filesys [ blocks ] DESCRIPTION
mkfs is used to build a Linux file system on a device, usually a hard disk partition. filesys is either the device name (e.g. /dev/hda1, /dev/sdb2) or the mount point (e.g. /, /usr, /home) for the file system. blocks is the number of blocks to be used for the file system. The exit code returned by mkfs is 0 on success and 1 on failure.
In actuality, mkfs is simply a front-end for the various file system builders (mkfs.fstype) available under Linux. The file system-specific builder is searched for in a number of directories like perhaps /sbin, /sbin/fs, /sbin/fs.d, /etc/fs, /etc (the precise list is defined at compile time but at least contains /sbin and /sbin/fs), and finally in the directories listed in the PATH enviroment variable. Please see the file system-specific builder manual pages for further details.
Please note the underlined information above.