For the case that you wish to revert a recently installed package that made several changes to dependencies (such as tensorflow), you can "roll back" to an earlier installation state via the following method:
conda list --revisions
conda install --revision [revision number]
The first command shows previous installation revisions (with dependencies) and the second reverts to whichever revision number you specify.
Note that if you wish to (re)install a later revision, you may have to sequentially reinstall all intermediate versions. If you had been at revision 23, reinstalled revision 20 and wish to return, you may have to run each:
conda install --revision 21
conda install --revision 22
conda install --revision 23