FAT32

Backup partition data (i.e. /boot/efi)

sudo mkdir /boot/efi_backup
sudo cp -r /boot/efi /boot/efi_backup

Unmount the partition

sudo umount /boot/efi

Create a new FAT32 filesystem (This will delete all data on the partition)

sudo mkfs.fat -F32 /dev/sdX1

Remount partition

sudo mount /dev/sdX1 /boot/efi

Restore backup

sudo cp -r /boot/efi_backup/* /boot/efi/

Verify partition size

df -h /boot/efi