Ortega grabs Dimi's head from Tak's room and carries it out into the rain, after wrapping it with a linen blanket to make it look less conspicuous. She ends up removing the stack from it in some alley, with rain pouring over her head and the proceeds to drop the head into some kind of drain.
Why does she bother with taking the head with her and doing it under the rain on the street? Why not do it in the relative comfort and privacy of the hotel instead and bring just the stack with her?
Her motivations are not completely obvious in this episode and they may change over time.
Her original intent may be related to her anger at finding out Kovacs has killed a large number of people during his breakout from Psychatek (not sure I've spelt that right) when he punished the entire organisation for torturing him. But the scene where she disposes of the head makes it look like her motivation has changed and she is more concerned with punishing Kadmin (whose stack she extracts from the head) and now ants to hide the physical evidence linking Kovacs to the crimes he has just committed (she wants to get Kadmin's stack back to police custody but never tells her colleagues how she obtained it).
It may be significant that this occurs not long after she has been forced to admit that some of her interest in Kovacs is because he is wearing the sleeve of her incarcerated lover, Riker, and she doesn't want to see the sleeve damaged irreparably. She also is told by Kovacs that Admin had framed Riker for the murder he was incarcerated for. This confuses her motivations a lot and not long after this she is in bed with Kovacs (or is it Riker or both as keeping track of the correct combination of body/person gets hard when you can inhabit multiple bodies?).
So I'm assuming she originally wanted to do something else with the head and changed her mind when she realised she didn't want to punish Kovacs (which might not help her get Riker back and might, in fact, stop any attempt to prove Riker was innocent). But she realised she could get Kadmin's stack back to the police station without associating it with the physical evidence of Kovacs's murder spree.
