Hi @Salma_Sarker,
It is far easier to make use of qiime rescript get-silva-data .... If you do not require the sequences you can simply run the following:
qiime rescript get-silva-data \
--p-version 138.2 \
--p-target SSURef_NR99 \
--p-ranks domain phylum class order family genus \
--p-no-download-sequences \
--output-dir ./silva-138.2-output \
--verbose
The --p-no-download-sequences flag will not download any sequences... but will result in an empty QZA sequence file. Run qiime rescript get-silva-data --help to check out other options. Note this action essentially wraps the silva taxonomy parser.
If you need to modify the taxonomy output checkout qiime rescript edit-taxonomy ....
-Hope this helps!