I'm not sure if the queries I am using are accurate.

Can anyone vouch for them?

EXEC sp_SpaceUsed

[database_name][database_size][unallocated space]

tempdb128801.31 MB127796.11 MB

[reserved][data][index_size][unused]

6984 KB3632 KB1576 KB1776 KB

Judging by these results, I should be able to reduce the data file size.

How can I confirm which internal processes are holding on to the TempDB space?