After attempting to delete a CSI in CA Mainframe Software Manager receives:
A pending installation for CSI data set: csiname.hlq.CSI is currently running,
or has an invalid entry in the database due to an unexpected failure of a Pending Installation.
USS, Tomcat, IE, Chrome, Datacom/AD
After clicking the CSI name under the SMP/E Environment tab, click the pending installations tab, does it say status pending or running? If it says running click refresh a few times until it says pending then try deleting it again.
CA Chorus™ Software Manager Administration Guide
Using the Pending Installation option under Settings, System Setting, Software Installation:
You could also recycle MSMTC.