So you want to get rid of the Linux partition?
In your search bar, type in disk Management. From there, you should be able to delete your old Linux partition and then "extend volume" to expand the Windows partition onto that space.
Also, Windows will set aside a 100 MB or so system reserve and it's probably not a good idea to delete that. Be careful!
Sometimes, Windows has issues with Linux partitions and you'll have to use FDisk or some other partition tool to delete the partition AND then go back and use Disk Management to extend the partition.